test-copies: add test chaining multiple merges

Right now, the copy tracing logic take the right decision for merges, but it
does not keep track of the right information about these decision and can fall
into later traps. We start with highlighting this possibility by adding new
tests, and we will fix them later.

Check the inline test documentation for details.

Differential Revision: https://phab.mercurial-scm.org/D9609

tests/test-copies-chain-merge.t

@@ -674,6 +674,113 b' rename information actually conflict wit'
   o  0 i-0 initial commit: a b h
   
 
+Decision from previous merge are properly chained with later merge
+------------------------------------------------------------------
+
+Subcase: chaining conflicting rename resolution
+```````````````````````````````````````````````
+
+The "mAEm" and "mEAm" case create a rename tracking conflict on file 'f'. We
+add more change on the respective branch and merge again. These second merge
+does not involve the file 'f' and the arbitration done within "mAEm" and "mEA"
+about that file should stay unchanged.
+
+  $ case_desc="chained merges (conflict -> simple) - same content everywhere"
+
+(extra unrelated changes)
+
+  $ hg up 'desc("a-2")'
+  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo j > unrelated-j
+  $ hg add unrelated-j
+  $ hg ci -m 'j-1: unrelated changes (based on the "a" series of changes)'
+  created new head
+
+  $ hg up 'desc("e-2")'
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 2 files removed, 0 files unresolved (changeset !)
+  $ echo k > unrelated-k
+  $ hg add unrelated-k
+  $ hg ci -m 'k-1: unrelated changes (based on "e" changes)'
+  created new head
+
+(merge variant 1)
+
+  $ hg up 'desc("mAEm")'
+  1 files updated, 0 files merged, 2 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved (changeset !)
+  $ hg merge 'desc("k-1")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mAE,Km: $case_desc"
+
+(merge variant 2)
+
+  $ hg up 'desc("k-1")'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
+
+  $ hg merge 'desc("mAEm")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mK,AEm: $case_desc"
+  created new head
+
+(merge variant 3)
+
+  $ hg up 'desc("mEAm")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge 'desc("j-1")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mEA,Jm: $case_desc"
+
+(merge variant 4)
+
+  $ hg up 'desc("j-1")'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
+  $ hg merge 'desc("mEAm")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mJ,EAm: $case_desc"
+  created new head
+
+
+  $ hg log -G --rev '::(desc("mAE,Km") + desc("mK,AEm") + desc("mEA,Jm") + desc("mJ,EAm"))'
+  @    42 mJ,EAm: chained merges (conflict -> simple) - same content everywhere
+  |\
+  +---o  41 mEA,Jm: chained merges (conflict -> simple) - same content everywhere
+  | |/
+  | | o    40 mK,AEm: chained merges (conflict -> simple) - same content everywhere
+  | | |\
+  | | +---o  39 mAE,Km: chained merges (conflict -> simple) - same content everywhere
+  | | | |/
+  | | | o  38 k-1: unrelated changes (based on "e" changes)
+  | | | |
+  | o | |  37 j-1: unrelated changes (based on the "a" series of changes)
+  | | | |
+  o-----+  20 mEAm-0 merge with copies info on both side - A side: rename d to f, E side: b to f, (same content for f) - the other way
+  |/ / /
+  | o /  19 mAEm-0 merge with copies info on both side - A side: rename d to f, E side: b to f, (same content for f) - 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
+  
+
 
 Summary of all created cases
 ----------------------------
@@ -698,7 +805,10 b' Summary of all created cases'
   i-0 initial commit: a b h
   i-1: a -move-> c
   i-2: c -move-> d
+  j-1: unrelated changes (based on the "a" series of changes)
+  k-1: unrelated changes (based on "e" changes)
   mABm-0 simple merge - A side: multiple renames, B side: unrelated update - the other way
+  mAE,Km: chained merges (conflict -> simple) - same content everywhere
   mAEm-0 merge with copies info on both side - A side: rename d to f, E side: b to f, (same content for f) - one way
   mBAm-0 simple merge - A side: multiple renames, B side: unrelated update - one way
   mBC-revert-m-0 merge explicitely revive deleted file - B side: unrelated change, C side: delete d (restored by merge) - the other way
@@ -713,6 +823,7 b' Summary of all created cases'
   mCH-delete-before-conflict-m-0 simple merge - C side: d is the results of renames then deleted, H side: d is result of another rename (same content as the other branch) - one way
   mDBm-0 simple merge - B side: unrelated update, D side: delete and recreate a file (with different content) - the other way
   mDGm-0 actual content merge, copies on one side - D side: delete and re-add (different content), G side: update content - one way
+  mEA,Jm: chained merges (conflict -> simple) - same content everywhere
   mEAm-0 merge with copies info on both side - A side: rename d to f, E side: b to f, (same content for f) - the other way
   mFBm-0 simple merge - B side: unrelated change, F side: overwrite d with a copy (from h->i->d) - the other way
   mFGm-0 merge - G side: content change, F side: copy overwrite, no content change - one way
@@ -720,6 +831,8 b' Summary of all created cases'
   mGDm-0 actual content merge, copies on one side - D side: delete and re-add (different content), G side: update content - the other way
   mGFm-0 merge - G side: content change, F side: copy overwrite, no content change - the other way
   mHC-delete-before-conflict-m-0 simple merge - C side: d is the results of renames then deleted, H side: d is result of another rename (same content as the other branch) - the other way
+  mJ,EAm: chained merges (conflict -> simple) - same content everywhere
+  mK,AEm: chained merges (conflict -> simple) - same content everywhere
 
 
 Test that sidedata computations during upgrades are correct
@@ -962,6 +1075,32 b' We upgrade a repository that is not usin'
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
+  ##### revision 37 #####
+  1 sidedata entries
+   entry-0014 size 24
+    '\x00\x00\x00\x01\x04\x00\x00\x00\x0b\x00\x00\x00\x00unrelated-j'
+  added      : unrelated-j, ;
+  ##### revision 38 #####
+  1 sidedata entries
+   entry-0014 size 24
+    '\x00\x00\x00\x01\x04\x00\x00\x00\x0b\x00\x00\x00\x00unrelated-k'
+  added      : unrelated-k, ;
+  ##### revision 39 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 40 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 41 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 42 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
 
 #endif
 
@@ -1801,3 +1940,62 b' rename information actually conflict wit'
   R a
   $ hg status --copies --rev 'desc("h-1")' --rev 'desc("mHC-delete-before-conflict-m")'
   R a
+
+Decision from previous merge are properly chained with later merge
+------------------------------------------------------------------
+
+
+Subcase: chaining conflicting rename resolution
+```````````````````````````````````````````````
+
+The "mAEm" and "mEAm" case create a rename tracking conflict on file 'f'. We
+add more change on the respective branch and merge again. These second merge
+does not involve the file 'f' and the arbitration done within "mAEm" and "mEA"
+about that file should stay unchanged.
+
+The result from mAEm is the same for the subsequent merge:
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mAEm")' f
+  A f
+    a (filelog !)
+    a (sidedata !)
+    a (upgraded !)
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mAE,Km")' f
+  A f
+    a (filelog !)
+    a (sidedata !)
+    a (upgraded !)
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mK,AEm")' f
+  A f
+    a (filelog !)
+    a (missing-correct-output sidedata !)
+    a (missing-correct-output upgraded !)
+    b (known-bad-output sidedata !)
+    b (known-bad-output upgraded !)
+
+
+The result from mEAm is the same for the subsequent merge:
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mEAm")' f
+  A f
+    a (filelog !)
+    b (sidedata !)
+    b (upgraded !)
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mEA,Jm")' f
+  A f
+    a (filelog !)
+    b (sidedata !)
+    b (upgraded !)
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mJ,EAm")' f
+  A f
+    a (filelog !)
+    b (missing-correct-output sidedata !)
+    b (missing-correct-output upgraded !)
+    a (known-bad-output sidedata !)
+    a (known-bad-output upgraded !)
+
+