copies: explain the "arbitrary" copy source pick in case of conflict

They are a logic and it is easy to explain, so lets explain it.

Differential Revision: https://phab.mercurial-scm.org/D9586

tests/test-copies-chain-merge.t

@@ -1,1685 +1,1707 b''
 #testcases filelog compatibility changeset sidedata upgraded
 
 =====================================================
 Test Copy tracing for chain of copies involving merge
 =====================================================
 
 This test files covers copies/rename case for a chains of commit where merges
 are involved. It cheks we do not have unwanted update of behavior and that the
 different options to retrieve copies behave correctly.
 
 
 Setup
 =====
 
 use git diff to see rename
 
   $ cat << EOF >> $HGRCPATH
   > [diff]
   > git=yes
   > [command-templates]
   > log={rev} {desc}\n
   > EOF
 
 #if compatibility
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > copies.read-from = compatibility
   > EOF
 #endif
 
 #if changeset
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > copies.read-from = changeset-only
   > copies.write-to = changeset-only
   > EOF
 #endif
 
 #if sidedata
   $ cat >> $HGRCPATH << EOF
   > [format]
   > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
 #endif
 
 
   $ hg init repo-chain
   $ cd repo-chain
 
 Add some linear rename initialy
 
   $ echo a > a
   $ echo b > b
   $ echo h > h
   $ hg ci -Am 'i-0 initial commit: a b h'
   adding a
   adding b
   adding h
   $ hg mv a c
   $ hg ci -Am 'i-1: a -move-> c'
   $ hg mv c d
   $ hg ci -Am 'i-2: c -move-> d'
   $ hg log -G
   @  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 And having another branch with renames on the other side
 
   $ hg mv d e
   $ hg ci -Am 'a-1: d -move-> e'
   $ hg mv e f
   $ hg ci -Am 'a-2: e -move-> f'
   $ hg log -G --rev '::.'
   @  4 a-2: e -move-> f
   |
   o  3 a-1: d -move-> e
   |
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Have a branching with nothing on one side
 
   $ hg up 'desc("i-2")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ echo foo > b
   $ hg ci -m 'b-1: b update'
   created new head
   $ hg log -G --rev '::.'
   @  5 b-1: b update
   |
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Create a branch that delete a file previous renamed
 
   $ hg up 'desc("i-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg rm d
   $ hg ci -m 'c-1 delete d'
   created new head
   $ hg log -G --rev '::.'
   @  6 c-1 delete d
   |
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Create a branch that delete a file previous renamed and recreate it
 
   $ hg up 'desc("i-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg rm d
   $ hg ci -m 'd-1 delete d'
   created new head
   $ echo bar > d
   $ hg add d
   $ hg ci -m 'd-2 re-add d'
   $ hg log -G --rev '::.'
   @  8 d-2 re-add d
   |
   o  7 d-1 delete d
   |
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Having another branch renaming a different file to the same filename as another
 
   $ hg up 'desc("i-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg mv b g
   $ hg ci -m 'e-1 b -move-> g'
   created new head
   $ hg mv g f
   $ hg ci -m 'e-2 g -move-> f'
   $ hg log -G --rev '::.'
   @  10 e-2 g -move-> f
   |
   o  9 e-1 b -move-> g
   |
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Setup all merge
 ===============
 
 This is done beforehand to validate that the upgrade process creates valid copy
 information.
 
 merging with unrelated change does not interfere with the renames
 ---------------------------------------------------------------
 
 - rename on one side
 - unrelated change on the other side
 
   $ hg up 'desc("b-1")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("a-2")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mBAm-0 simple merge - one way'
   $ hg up 'desc("a-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mABm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mABm")+desc("mBAm"))'
   @    12 mABm-0 simple merge - the other way
   |\
   +---o  11 mBAm-0 simple merge - one way
   | |/
   | o  5 b-1: b update
   | |
   o |  4 a-2: e -move-> f
   | |
   o |  3 a-1: d -move-> e
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 merging with the side having a delete
 -------------------------------------
 
 case summary:
 - one with change to an unrelated file
 - one deleting the change
 and recreate an unrelated file after the merge
 
   $ hg up 'desc("b-1")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("c-1")'
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mBCm-0 simple merge - one way'
   $ echo bar > d
   $ hg add d
   $ hg ci -m 'mBCm-1 re-add d'
   $ hg up 'desc("c-1")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mCBm-0 simple merge - the other way'
   created new head
   $ echo bar > d
   $ hg add d
   $ hg ci -m 'mCBm-1 re-add d'
   $ hg log -G --rev '::(desc("mCBm")+desc("mBCm"))'
   @  16 mCBm-1 re-add d
   |
   o    15 mCBm-0 simple merge - the other way
   |\
   | | o  14 mBCm-1 re-add d
   | | |
   +---o  13 mBCm-0 simple merge - one way
   | |/
   | o  6 c-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 Comparing with a merge re-adding the file afterward
 ---------------------------------------------------
 
 Merge:
 - one with change to an unrelated file
 - one deleting and recreating the change
 
   $ hg up 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("d-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mBDm-0 simple merge - one way'
   $ hg up 'desc("d-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mDBm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mDBm")+desc("mBDm"))'
   @    18 mDBm-0 simple merge - the other way
   |\
   +---o  17 mBDm-0 simple merge - one way
   | |/
   | o  8 d-2 re-add d
   | |
   | o  7 d-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 Comparing with a merge with colliding rename
 --------------------------------------------
 
 - the "e-" branch renaming b to f (through 'g')
 - the "a-" branch renaming d to f (through e)
 
   $ hg up 'desc("a-2")'
   2 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("e-2")' --tool :union
   merging f
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mAEm-0 simple merge - one way'
   $ hg up 'desc("e-2")'
   2 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("a-2")' --tool :union
   merging f
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mEAm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mAEm")+desc("mEAm"))'
   @    20 mEAm-0 simple merge - the other way
   |\
   +---o  19 mAEm-0 simple merge - one way
   | |/
   | o  10 e-2 g -move-> f
   | |
   | o  9 e-1 b -move-> g
   | |
   o |  4 a-2: e -move-> f
   | |
   o |  3 a-1: d -move-> e
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 Merge:
 - one with change to an unrelated file (b)
 - one overwriting a file (d) with a rename (from h to i to d)
 
   $ hg up 'desc("i-2")'
   2 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg mv h i
   $ hg commit -m "f-1: rename h -> i"
   created new head
   $ hg mv --force i d
   $ hg commit -m "f-2: rename i -> d"
   $ hg debugindex d
      rev linkrev nodeid       p1           p2
        0       2 169be882533b 000000000000 000000000000 (no-changeset !)
        0       2 b789fdd96dc2 000000000000 000000000000 (changeset !)
        1       8 b004912a8510 000000000000 000000000000
        2      22 4a067cf8965d 000000000000 000000000000 (no-changeset !)
        2      22 fe6f8b4f507f 000000000000 000000000000 (changeset !)
   $ hg up 'desc("b-1")'
   3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("f-2")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mBFm-0 simple merge - one way'
   $ hg up 'desc("f-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mFBm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mBFm")+desc("mFBm"))'
   @    24 mFBm-0 simple merge - the other way
   |\
   +---o  23 mBFm-0 simple merge - one way
   | |/
   | o  22 f-2: rename i -> d
   | |
   | o  21 f-1: rename h -> i
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 Merge:
 - one with change to a file
 - one deleting and recreating the file
 
 Unlike in the 'BD/DB' cases, an actual merge happened here. So we should
 consider history and rename on both branch of the merge.
 
   $ hg up 'desc("i-2")'
   3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo "some update" >> d
   $ hg commit -m "g-1: update d"
   created new head
   $ hg up 'desc("d-2")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("g-1")' --tool :union
   merging d
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mDGm-0 simple merge - one way'
   $ hg up 'desc("g-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("d-2")' --tool :union
   merging d
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mGDm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mDGm")+desc("mGDm"))'
   @    27 mGDm-0 simple merge - the other way
   |\
   +---o  26 mDGm-0 simple merge - one way
   | |/
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   | |
   o |  7 d-1 delete d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 Merge:
 - one with change to a file (d)
 - one overwriting that file with a rename (from h to i, to d)
 
 This case is similar to BF/FB, but an actual merge happens, so both side of the
 history are relevant.
 
 Note:
 | In this case, the merge get conflicting information since on one side we have
 | "a -> c -> d". and one the other one we have "h -> i -> d".
 |
 | The current code arbitrarily pick one side
 
   $ hg up 'desc("f-2")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("g-1")' --tool :union
   merging d
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mFGm-0 simple merge - one way'
   created new head
   $ hg up 'desc("g-1")'
   2 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("f-2")' --tool :union
   merging d
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m 'mGFm-0 simple merge - the other way'
   created new head
   $ hg log -G --rev '::(desc("mGFm")+desc("mFGm"))'
   @    29 mGFm-0 simple merge - the other way
   |\
   +---o  28 mFGm-0 simple merge - one way
   | |/
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   | |
   o |  21 f-1: rename h -> i
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 Comparing with merging with a deletion (and keeping the file)
 -------------------------------------------------------------
 
 Merge:
 - one removing a file (d)
 - one updating that file
 - the merge keep the modified version of the file (canceling the delete)
 
 In this case, the file keep on living after the merge. So we should not drop its
 copy tracing chain.
 
   $ hg up 'desc("c-1")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("g-1")'
   file 'd' was deleted in local [working copy] but was modified in other [merge rev].
   You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved.
   What do you want to do? u
   0 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
   [1]
   $ hg resolve -t :other d
   (no more unresolved files)
   $ hg ci -m "mCGm-0"
   created new head
 
   $ hg up 'desc("g-1")'
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("c-1")'
   file 'd' was deleted in other [merge rev] but was modified in local [working copy].
   You can use (c)hanged version, (d)elete, or leave (u)nresolved.
   What do you want to do? u
   0 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
   [1]
   $ hg resolve -t :local d
   (no more unresolved files)
   $ hg ci -m "mGCm-0"
   created new head
 
   $ hg log -G --rev '::(desc("mCGm")+desc("mGCm"))'
   @    31 mGCm-0
   |\
   +---o  30 mCGm-0
   | |/
   | o  25 g-1: update d
   | |
   o |  6 c-1 delete d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
 
 Comparing with merge restoring an untouched deleted file
 --------------------------------------------------------
 
 Merge:
 - one removing a file (d)
 - one leaving the file untouched
 - the merge actively restore the file to the same content.
 
 In this case, the file keep on living after the merge. So we should not drop its
 copy tracing chain.
 
   $ hg up 'desc("c-1")'
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("b-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg revert --rev 'desc("b-1")' d
   $ hg ci -m "mCB-revert-m-0"
   created new head
 
   $ hg up 'desc("b-1")'
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("c-1")'
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg revert --rev 'desc("b-1")' d
   $ hg ci -m "mBC-revert-m-0"
   created new head
 
   $ hg log -G --rev '::(desc("mCB-revert-m")+desc("mBC-revert-m"))'
   @    33 mBC-revert-m-0
   |\
   +---o  32 mCB-revert-m-0
   | |/
   | o  6 c-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 
   $ hg up null --quiet
 
 Merging a branch where a rename was deleted with a branch where the same file was renamed
 ------------------------------------------------------------------------------------------
 
 Create a "conflicting" merge where `d` get removed on one branch before its
 rename information actually conflict with the other branch.
 
 (the copy information from the branch that was not deleted should win).
 
   $ hg up 'desc("i-0")'
   3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg mv b d
   $ hg ci -m "h-1: b -(move)-> d"
   created new head
 
   $ hg up 'desc("c-1")'
   1 files updated, 0 files merged, 2 files removed, 0 files unresolved
   $ hg merge 'desc("h-1")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m "mCH-delete-before-conflict-m-0"
 
   $ hg up 'desc("h-1")'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg merge 'desc("c-1")'
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m "mHC-delete-before-conflict-m-0"
   created new head
   $ hg log -G --rev '::(desc("mCH-delete-before-conflict-m")+desc("mHC-delete-before-conflict-m"))'
   @    36 mHC-delete-before-conflict-m-0
   |\
   +---o  35 mCH-delete-before-conflict-m-0
   | |/
   | o  34 h-1: b -(move)-> d
   | |
   o |  6 c-1 delete d
   | |
   o |  2 i-2: c -move-> d
   | |
   o |  1 i-1: a -move-> c
   |/
   o  0 i-0 initial commit: a b h
   
 
 
 Test that sidedata computations during upgrades are correct
 ===========================================================
 
 We upgrade a repository that is not using sidedata (the filelog case) and
  check that the same side data have been generated as if they were computed at
  commit time.
 
 
 #if upgraded
   $ cat >> $HGRCPATH << EOF
   > [format]
   > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   exp-sharesafe:       no     no      no
   sparserevlog:       yes    yes     yes
   sidedata:            no    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no    yes      no
   plain-cl-delta:     yes    yes     yes
   compression:        * (glob)
   compression-level:  default default default
   $ hg debugupgraderepo --run --quiet
   upgrade will perform the following actions:
   
   requirements
      preserved: * (glob)
      added: exp-copies-sidedata-changeset, exp-sidedata-flag
   
   processed revlogs:
     - all-filelogs
     - changelog
     - manifest
   
 #endif
 
 
 #if no-compatibility no-filelog no-changeset
 
   $ for rev in `hg log --rev 'all()' -T '{rev}\n'`; do
   >     echo "##### revision $rev #####"
   >     hg debugsidedata -c -v -- $rev
   >     hg debugchangedfiles $rev
   > done
   ##### revision 0 #####
   1 sidedata entries
    entry-0014 size 34
     '\x00\x00\x00\x03\x04\x00\x00\x00\x01\x00\x00\x00\x00\x04\x00\x00\x00\x02\x00\x00\x00\x00\x04\x00\x00\x00\x03\x00\x00\x00\x00abh'
   added      : a, ;
   added      : b, ;
   added      : h, ;
   ##### revision 1 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00ac'
   removed    : a, ;
   added    p1: c, a;
   ##### revision 2 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00cd'
   removed    : c, ;
   added    p1: d, c;
   ##### revision 3 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00de'
   removed    : d, ;
   added    p1: e, d;
   ##### revision 4 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00ef'
   removed    : e, ;
   added    p1: f, e;
   ##### revision 5 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00b'
   touched    : b, ;
   ##### revision 6 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x0c\x00\x00\x00\x01\x00\x00\x00\x00d'
   removed    : d, ;
   ##### revision 7 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x0c\x00\x00\x00\x01\x00\x00\x00\x00d'
   removed    : d, ;
   ##### revision 8 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x04\x00\x00\x00\x01\x00\x00\x00\x00d'
   added      : d, ;
   ##### revision 9 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00bg'
   removed    : b, ;
   added    p1: g, b;
   ##### revision 10 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x06\x00\x00\x00\x01\x00\x00\x00\x01\x0c\x00\x00\x00\x02\x00\x00\x00\x00fg'
   added    p1: f, g;
   removed    : g, ;
   ##### revision 11 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 12 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 13 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 14 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x04\x00\x00\x00\x01\x00\x00\x00\x00d'
   added      : d, ;
   ##### revision 15 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 16 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x04\x00\x00\x00\x01\x00\x00\x00\x00d'
   added      : d, ;
   ##### revision 17 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 18 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 19 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00f'
   merged     : f, ;
   ##### revision 20 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00f'
   merged     : f, ;
   ##### revision 21 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00hi'
   removed    : h, ;
   added    p1: i, h;
   ##### revision 22 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x16\x00\x00\x00\x01\x00\x00\x00\x01\x0c\x00\x00\x00\x02\x00\x00\x00\x00di'
   touched  p1: d, i;
   removed    : i, ;
   ##### revision 23 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 24 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 25 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d'
   touched    : d, ;
   ##### revision 26 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d'
   merged     : d, ;
   ##### revision 27 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d'
   merged     : d, ;
   ##### revision 28 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d'
   merged     : d, ;
   ##### revision 29 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d'
   merged     : d, ;
   ##### revision 30 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x10\x00\x00\x00\x01\x00\x00\x00\x00d'
   salvaged   : d, ;
   ##### revision 31 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x10\x00\x00\x00\x01\x00\x00\x00\x00d'
   salvaged   : d, ;
   ##### revision 32 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x10\x00\x00\x00\x01\x00\x00\x00\x00d'
   salvaged   : d, ;
   ##### revision 33 #####
   1 sidedata entries
    entry-0014 size 14
     '\x00\x00\x00\x01\x10\x00\x00\x00\x01\x00\x00\x00\x00d'
   salvaged   : d, ;
   ##### revision 34 #####
   1 sidedata entries
    entry-0014 size 24
     '\x00\x00\x00\x02\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00bd'
   removed    : b, ;
   added    p1: d, b;
   ##### revision 35 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
   ##### revision 36 #####
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
 
 #endif
 
 
 Test copy information chaining
 ==============================
 
 Check that matching only affect the destination and not intermediate path
 -------------------------------------------------------------------------
 
 The two status call should give the same value for f
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("a-2")'
   A f
     a
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("a-2")' f
   A f
     a (no-changeset no-compatibility !)
 
 merging with unrelated change does not interfere with the renames
 ---------------------------------------------------------------
 
 - rename on one side
 - unrelated change on the other side
 
   $ hg log -G --rev '::(desc("mABm")+desc("mBAm"))'
   o    12 mABm-0 simple merge - the other way
   |\
   +---o  11 mBAm-0 simple merge - one way
   | |/
   | o  5 b-1: b update
   | |
   o |  4 a-2: e -move-> f
   | |
   o |  3 a-1: d -move-> e
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mABm")'
   A f
     d
   R d
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBAm")'
   A f
     d
   R d
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mABm")'
   M b
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mBAm")'
   M b
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mABm")'
   M b
   A f
     d
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mBAm")'
   M b
   A f
     d
   R d
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mABm")'
   M b
   A f
     a
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBAm")'
   M b
   A f
     a
   R a
 
 merging with the side having a delete
 -------------------------------------
 
 case summary:
 - one with change to an unrelated file
 - one deleting the change
 and recreate an unrelated file after the merge
 
   $ hg log -G --rev '::(desc("mCBm")+desc("mBCm"))'
   o  16 mCBm-1 re-add d
   |
   o    15 mCBm-0 simple merge - the other way
   |\
   | | o  14 mBCm-1 re-add d
   | | |
   +---o  13 mBCm-0 simple merge - one way
   | |/
   | o  6 c-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 - comparing from the merge
 
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBCm-0")'
   R d
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mCBm-0")'
   R d
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mBCm-0")'
   M b
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mCBm-0")'
   M b
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mBCm-0")'
   M b
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mCBm-0")'
   M b
   R d
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBCm-0")'
   M b
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCBm-0")'
   M b
   R a
 
 - comparing with the merge children re-adding the file
 
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBCm-1")'
   M d
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mCBm-1")'
   M d
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mBCm-1")'
   M b
   A d
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mCBm-1")'
   M b
   A d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mBCm-1")'
   M b
   M d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mCBm-1")'
   M b
   M d
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBCm-1")'
   M b
   A d
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCBm-1")'
   M b
   A d
   R a
 
 Comparing with a merge re-adding the file afterward
 ---------------------------------------------------
 
 Merge:
 - one with change to an unrelated file
 - one deleting and recreating the change
 
   $ hg log -G --rev '::(desc("mDBm")+desc("mBDm"))'
   o    18 mDBm-0 simple merge - the other way
   |\
   +---o  17 mBDm-0 simple merge - one way
   | |/
   | o  8 d-2 re-add d
   | |
   | o  7 d-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBDm-0")'
   M d
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mDBm-0")'
   M d
   $ hg status --copies --rev 'desc("d-2")' --rev 'desc("mBDm-0")'
   M b
   $ hg status --copies --rev 'desc("d-2")' --rev 'desc("mDBm-0")'
   M b
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mBDm-0")'
   M b
   M d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mDBm-0")'
   M b
   M d
 
 The bugs makes recorded copy is different depending of where we started the merge from since
 
   $ hg manifest --debug --rev 'desc("mBDm-0")' | grep '644   d'
   b004912a8510032a0350a74daa2803dadfb00e12 644   d
   $ hg manifest --debug --rev 'desc("mDBm-0")' | grep '644   d'
   b004912a8510032a0350a74daa2803dadfb00e12 644   d
 
   $ hg manifest --debug --rev 'desc("d-2")' | grep '644   d'
   b004912a8510032a0350a74daa2803dadfb00e12 644   d
   $ hg manifest --debug --rev 'desc("b-1")' | grep '644   d'
   169be882533bc917905d46c0c951aa9a1e288dcf 644   d (no-changeset !)
   b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   d (changeset !)
   $ hg debugindex d | head -n 4
      rev linkrev nodeid       p1           p2
        0       2 169be882533b 000000000000 000000000000 (no-changeset !)
        0       2 b789fdd96dc2 000000000000 000000000000 (changeset !)
        1       8 b004912a8510 000000000000 000000000000
        2      22 4a067cf8965d 000000000000 000000000000 (no-changeset !)
        2      22 fe6f8b4f507f 000000000000 000000000000 (changeset !)
 
 Log output should not include a merge commit as it did not happen
 
   $ hg log -Gfr 'desc("mBDm-0")' d
   o  8 d-2 re-add d
   |
   ~
 
   $ hg log -Gfr 'desc("mDBm-0")' d
   o  8 d-2 re-add d
   |
   ~
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBDm-0")'
   M b
   A d
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mDBm-0")'
   M b
   A d
   R a
 
 
 Comparing with a merge with colliding rename
 --------------------------------------------
 
 - the "e-" branch renaming b to f (through 'g')
 - the "a-" branch renaming d to f (through e)
 
   $ hg log -G --rev '::(desc("mAEm")+desc("mEAm"))'
   o    20 mEAm-0 simple merge - the other way
   |\
   +---o  19 mAEm-0 simple merge - one way
   | |/
   | o  10 e-2 g -move-> f
   | |
   | o  9 e-1 b -move-> g
   | |
   o |  4 a-2: e -move-> f
   | |
   o |  3 a-1: d -move-> e
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 #if no-changeset
   $ hg manifest --debug --rev 'desc("mAEm-0")' | grep '644   f'
   c39c6083dad048d5138618a46f123e2f397f4f18 644   f
   $ hg manifest --debug --rev 'desc("mEAm-0")' | grep '644   f'
   a9a8bc3860c9d8fa5f2f7e6ea8d40498322737fd 644   f
   $ hg manifest --debug --rev 'desc("a-2")' | grep '644   f'
   263ea25e220aaeb7b9bac551c702037849aa75e8 644   f
   $ hg manifest --debug --rev 'desc("e-2")' | grep '644   f'
   71b9b7e73d973572ade6dd765477fcee6890e8b1 644   f
   $ hg debugindex f
      rev linkrev nodeid       p1           p2
        0       4 263ea25e220a 000000000000 000000000000
        1      10 71b9b7e73d97 000000000000 000000000000
        2      19 c39c6083dad0 263ea25e220a 71b9b7e73d97
        3      20 a9a8bc3860c9 71b9b7e73d97 263ea25e220a
 #else
   $ hg manifest --debug --rev 'desc("mAEm-0")' | grep '644   f'
   498e8799f49f9da1ca06bb2d6d4accf165c5b572 644   f
   $ hg manifest --debug --rev 'desc("mEAm-0")' | grep '644   f'
   c5b506a7118667a38a9c9348a1f63b679e382f57 644   f
   $ hg manifest --debug --rev 'desc("a-2")' | grep '644   f'
   b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   f
   $ hg manifest --debug --rev 'desc("e-2")' | grep '644   f'
   1e88685f5ddec574a34c70af492f95b6debc8741 644   f
   $ hg debugindex f
      rev linkrev nodeid       p1           p2
        0       4 b789fdd96dc2 000000000000 000000000000
        1      10 1e88685f5dde 000000000000 000000000000
        2      19 498e8799f49f b789fdd96dc2 1e88685f5dde
        3      20 c5b506a71186 1e88685f5dde b789fdd96dc2
 #endif
 
 # Here the filelog based implementation is not looking at the rename
 # information (because the file exist on both side). However the changelog
 # based on works fine. We have different output.
 
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mAEm-0")'
   M f
     b (no-filelog !)
   R b
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mEAm-0")'
   M f
     b (no-filelog !)
   R b
   $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mAEm-0")'
   M f
     d (no-filelog !)
   R d
   $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mEAm-0")'
   M f
     d (no-filelog !)
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("a-2")'
   A f
     d
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("e-2")'
   A f
     b
   R b
 
 # From here, we run status against revision where both source file exists.
 #
 # The filelog based implementation picks an arbitrary side based on revision
 # numbers. So the same side "wins" whatever the parents order is. This is
 # sub-optimal because depending on revision numbers means the result can be
 # different from one repository to the next.
 #
 # The changeset based algorithm use the parent order to break tie on conflicting
 # information and will have a different order depending on who is p1 and p2.
 # That order is stable accross repositories. (data from p1 prevails)
 
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mAEm-0")'
   A f
     d
   R b
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("mEAm-0")'
   A f
     d (filelog !)
     b (no-filelog !)
   R b
   R d
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mAEm-0")'
   A f
     a
   R a
   R b
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mEAm-0")'
   A f
     a (filelog !)
     b (no-filelog !)
   R a
   R b
 
 
 Note:
 | In this case, one of the merge wrongly record a merge while there is none.
 | This lead to bad copy tracing information to be dug up.
 
 
 Merge:
 - one with change to an unrelated file (b)
 - one overwriting a file (d) with a rename (from h to i to d)
 
   $ hg log -G --rev '::(desc("mBFm")+desc("mFBm"))'
   o    24 mFBm-0 simple merge - the other way
   |\
   +---o  23 mBFm-0 simple merge - one way
   | |/
   | o  22 f-2: rename i -> d
   | |
   | o  21 f-1: rename h -> i
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBFm-0")'
   M b
   A d
     h
   R a
   R h
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mFBm-0")'
   M b
   A d
     h
   R a
   R h
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBFm-0")'
   M d
     h (no-filelog !)
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mBFm-0")'
   M b
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mBFm-0")'
   M b
   M d
     i (no-filelog !)
   R i
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mFBm-0")'
   M d
     h (no-filelog !)
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mFBm-0")'
   M b
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mFBm-0")'
   M b
   M d
     i (no-filelog !)
   R i
 
 #if no-changeset
   $ hg log -Gfr 'desc("mBFm-0")' d
   o  22 f-2: rename i -> d
   |
   o  21 f-1: rename h -> i
   :
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mBFm-0")' d
   o  22 f-2: rename i -> d
   |
   ~
 #endif
 
 #if no-changeset
   $ hg log -Gfr 'desc("mFBm-0")' d
   o  22 f-2: rename i -> d
   |
   o  21 f-1: rename h -> i
   :
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mFBm-0")' d
   o  22 f-2: rename i -> d
   |
   ~
 #endif
 
 
 Merge:
 - one with change to a file
 - one deleting and recreating the file
 
 Unlike in the 'BD/DB' cases, an actual merge happened here. So we should
 consider history and rename on both branch of the merge.
 
   $ hg log -G --rev '::(desc("mDGm")+desc("mGDm"))'
   o    27 mGDm-0 simple merge - the other way
   |\
   +---o  26 mDGm-0 simple merge - one way
   | |/
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   | |
   o |  7 d-1 delete d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 One side of the merge have a long history with rename. The other side of the
 merge point to a new file with a smaller history. Each side is "valid".
 
 (and again the filelog based algorithm only explore one, with a pick based on
 revision numbers)
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mDGm-0")'
   A d
     a (filelog !)
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mGDm-0")'
   A d
     a
   R a
   $ hg status --copies --rev 'desc("d-2")' --rev 'desc("mDGm-0")'
   M d
   $ hg status --copies --rev 'desc("d-2")' --rev 'desc("mGDm-0")'
   M d
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mDGm-0")'
   M d
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mGDm-0")'
   M d
 
 #if no-changeset
   $ hg log -Gfr 'desc("mDGm-0")' d
   o    26 mDGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mDGm-0")' d
   o    26 mDGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   |/
   o  2 i-2: c -move-> d
   |
   ~
 #endif
 
 
 #if no-changeset
   $ hg log -Gfr 'desc("mDGm-0")' d
   o    26 mDGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mDGm-0")' d
   o    26 mDGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  8 d-2 re-add d
   |/
   o  2 i-2: c -move-> d
   |
   ~
 #endif
 
 
 Merge:
 - one with change to a file (d)
 - one overwriting that file with a rename (from h to i, to d)
 
 This case is similar to BF/FB, but an actual merge happens, so both side of the
 history are relevant.
 
-Note:
-| In this case, the merge get conflicting information since on one side we have
-| "a -> c -> d". and one the other one we have "h -> i -> d".
-|
-| The current code arbitrarily pick one side
 
   $ hg log -G --rev '::(desc("mGFm")+desc("mFGm"))'
   o    29 mGFm-0 simple merge - the other way
   |\
   +---o  28 mFGm-0 simple merge - one way
   | |/
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   | |
   o |  21 f-1: rename h -> i
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
+
+Note:
+| In this case, the merge get conflicting information since on one side we have
+| "a -> c -> d". and one the other one we have "h -> i -> d".
+|
+| The current code arbitrarily pick one side depending the ordering of the merged hash:
+
+In this case, the file hash from "f-2" is lower, so it will be `p1` of the resulting filenode its copy tracing information will win (and trace back to "h"):
+
+Details on this hash ordering pick:
+
+  $ hg manifest --debug 'desc("g-1")' | egrep 'd$'
+  f2b277c39e0d2bbac99d8aae075c0d8b5304d266 644   d (no-changeset !)
+  4ff57b4e8dceedb487e70e6965ea188a7c042cca 644   d (changeset !)
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("g-1")' d
+  A d
+    a (no-changeset no-compatibility !)
+
+  $ hg manifest --debug 'desc("f-2")' | egrep 'd$'
+  4a067cf8965d1bfff130057ade26b44f580231be 644   d (no-changeset !)
+  fe6f8b4f507fe3eb524c527192a84920a4288dac 644   d (changeset !)
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("f-2")' d
+  A d
+    h (no-changeset no-compatibility !)
+
+Copy tracing data on the resulting merge:
+
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mFGm-0")'
   A d
     h
   R a
   R h
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mGFm-0")'
   A d
     a (no-filelog !)
     h (filelog !)
   R a
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mFGm-0")'
   M d
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mGFm-0")'
   M d
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mFGm-0")'
   M d
     i (no-filelog !)
   R i
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mGFm-0")'
   M d
     i (no-filelog !)
   R i
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mFGm-0")'
   M d
     h (no-filelog !)
   R h
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mGFm-0")'
   M d
     h (no-filelog !)
   R h
 
 #if no-changeset
   $ hg log -Gfr 'desc("mFGm-0")' d
   o    28 mFGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   | |
   o |  21 f-1: rename h -> i
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mFGm-0")' d
   o    28 mFGm-0 simple merge - one way
   |\
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   |/
   o  2 i-2: c -move-> d
   |
   ~
 #endif
 
 #if no-changeset
   $ hg log -Gfr 'desc("mGFm-0")' d
   o    29 mGFm-0 simple merge - the other way
   |\
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   | |
   o |  21 f-1: rename h -> i
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mGFm-0")' d
   o    29 mGFm-0 simple merge - the other way
   |\
   | o  25 g-1: update d
   | |
   o |  22 f-2: rename i -> d
   |/
   o  2 i-2: c -move-> d
   |
   ~
 #endif
 
 
 Comparing with merging with a deletion (and keeping the file)
 -------------------------------------------------------------
 
 Merge:
 - one removing a file (d)
 - one updating that file
 - the merge keep the modified version of the file (canceling the delete)
 
 In this case, the file keep on living after the merge. So we should not drop its
 copy tracing chain.
 
   $ hg log -G --rev '::(desc("mCGm")+desc("mGCm"))'
   o    31 mGCm-0
   |\
   +---o  30 mCGm-0
   | |/
   | o  25 g-1: update d
   | |
   o |  6 c-1 delete d
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 'a' is the copy source of 'd'
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCGm-0")'
   A d
     a (no-compatibility no-changeset !)
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mGCm-0")'
   A d
     a (no-compatibility no-changeset !)
   R a
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mCGm-0")'
   A d
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mGCm-0")'
   A d
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mCGm-0")'
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mGCm-0")'
 
 
 Comparing with merge restoring an untouched deleted file
 --------------------------------------------------------
 
 Merge:
 - one removing a file (d)
 - one leaving the file untouched
 - the merge actively restore the file to the same content.
 
 In this case, the file keep on living after the merge. So we should not drop its
 copy tracing chain.
 
   $ hg log -G --rev '::(desc("mCB-revert-m")+desc("mBC-revert-m"))'
   o    33 mBC-revert-m-0
   |\
   +---o  32 mCB-revert-m-0
   | |/
   | o  6 c-1 delete d
   | |
   o |  5 b-1: b update
   |/
   o  2 i-2: c -move-> d
   |
   o  1 i-1: a -move-> c
   |
   o  0 i-0 initial commit: a b h
   
 
 'a' is the the copy source of 'd'
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCB-revert-m-0")'
   M b
   A d
     a (no-compatibility no-changeset !)
   R a
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBC-revert-m-0")'
   M b
   A d
     a (no-compatibility no-changeset !)
   R a
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mCB-revert-m-0")'
   M b
   A d
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mBC-revert-m-0")'
   M b
   A d
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mCB-revert-m-0")'
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBC-revert-m-0")'
 
 
 Merging a branch where a rename was deleted with a branch where the same file was renamed
 ------------------------------------------------------------------------------------------
 
 Create a "conflicting" merge where `d` get removed on one branch before its
 rename information actually conflict with the other branch.
 
 (the copy information from the branch that was not deleted should win).
 
   $ hg log -G --rev '::(desc("mCH-delete-before-conflict-m")+desc("mHC-delete-before-conflict-m"))'
   @    36 mHC-delete-before-conflict-m-0
   |\
   +---o  35 mCH-delete-before-conflict-m-0
   | |/
   | o  34 h-1: b -(move)-> d
   | |
   o |  6 c-1 delete d
   | |
   o |  2 i-2: c -move-> d
   | |
   o |  1 i-1: a -move-> c
   |/
   o  0 i-0 initial commit: a b h
   
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCH-delete-before-conflict-m")'
   A d
     b (no-compatibility no-changeset !)
   R a
   R b
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mHC-delete-before-conflict-m")'
   A d
     b
   R a
   R b
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mCH-delete-before-conflict-m")'
   A d
     b
   R b
   $ hg status --copies --rev 'desc("c-1")' --rev 'desc("mHC-delete-before-conflict-m")'
   A d
     b
   R b
   $ hg status --copies --rev 'desc("h-1")' --rev 'desc("mCH-delete-before-conflict-m")'
   R a
   $ hg status --copies --rev 'desc("h-1")' --rev 'desc("mHC-delete-before-conflict-m")'
   R a