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/D9610

tests/test-copies-chain-merge.t

@@ -781,6 +781,91 b' about that file should stay unchanged.'
   o  0 i-0 initial commit: a b h
   
 
+Subcase: chaining salvage information during a merge
+````````````````````````````````````````````````````
+
+We add more change on the branch were the file was deleted. merging again
+should preserve the fact eh file was salvaged.
+
+  $ case_desc="chained merges (salvaged -> simple) - same content (when the file exists)"
+
+(creating the change)
+
+  $ hg up 'desc("c-1")'
+  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ echo l > unrelated-l
+  $ hg add unrelated-l
+  $ hg ci -m 'l-1: unrelated changes (based on "c" changes)'
+  created new head
+
+(Merge variant 1)
+
+  $ hg up 'desc("mBC-revert-m")'
+  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge 'desc("l-1")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mBC+revert,Lm: $case_desc"
+
+(Merge variant 2)
+
+  $ hg up 'desc("mCB-revert-m")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge 'desc("l-1")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mCB+revert,Lm: $case_desc"
+
+(Merge variant 3)
+
+  $ hg up 'desc("l-1")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+
+  $ hg merge 'desc("mBC-revert-m")'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mL,BC+revertm: $case_desc"
+  created new head
+
+(Merge variant 4)
+
+  $ hg up 'desc("l-1")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+
+  $ hg merge 'desc("mCB-revert-m")'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "mL,CB+revertm: $case_desc"
+  created new head
+
+  $ hg log -G --rev '::(desc("mBC+revert,Lm") + desc("mCB+revert,Lm") + desc("mL,BC+revertm") + desc("mL,CB+revertm"))'
+  @    47 mL,CB+revertm: chained merges (salvaged -> simple) - same content (when the file exists)
+  |\
+  | | o  46 mL,BC+revertm: chained merges (salvaged -> simple) - same content (when the file exists)
+  | |/|
+  +-+---o  45 mCB+revert,Lm: chained merges (salvaged -> simple) - same content (when the file exists)
+  | | |
+  | +---o  44 mBC+revert,Lm: chained merges (salvaged -> simple) - same content (when the file exists)
+  | | |/
+  | o |  43 l-1: unrelated changes (based on "c" changes)
+  | | |
+  | | o  33 mBC-revert-m-0 merge explicitely revive deleted file - B side: unrelated change, C side: delete d (restored by merge) - the other way
+  | |/|
+  o---+  32 mCB-revert-m-0 merge explicitely revive deleted file - B side: unrelated change, C side: delete d (restored by 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
+  
+
+
+
 
 Summary of all created cases
 ----------------------------
@@ -807,15 +892,18 b' Summary of all created cases'
   i-2: c -move-> d
   j-1: unrelated changes (based on the "a" series of changes)
   k-1: unrelated changes (based on "e" changes)
+  l-1: unrelated changes (based on "c" 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,Lm: chained merges (salvaged -> simple) - same content (when the file exists)
   mBC-revert-m-0 merge explicitely revive deleted file - B side: unrelated change, C side: delete d (restored by merge) - the other way
   mBCm-0 simple merge - C side: delete a file with copies history , B side: unrelated update - one way
   mBCm-1 re-add d
   mBDm-0 simple merge - B side: unrelated update, D side: delete and recreate a file (with different content) - one way
   mBFm-0 simple merge - B side: unrelated change, F side: overwrite d with a copy (from h->i->d) - one way
+  mCB+revert,Lm: chained merges (salvaged -> simple) - same content (when the file exists)
   mCB-revert-m-0 merge explicitely revive deleted file - B side: unrelated change, C side: delete d (restored by merge) - one way
   mCBm-0 simple merge - C side: delete a file with copies history , B side: unrelated update - the other way
   mCBm-1 re-add d
@@ -833,6 +921,8 b' Summary of all created cases'
   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
+  mL,BC+revertm: chained merges (salvaged -> simple) - same content (when the file exists)
+  mL,CB+revertm: chained merges (salvaged -> simple) - same content (when the file exists)
 
 
 Test that sidedata computations during upgrades are correct
@@ -1101,6 +1191,27 b' We upgrade a repository that is not usin'
   1 sidedata entries
    entry-0014 size 4
     '\x00\x00\x00\x00'
+  ##### revision 43 #####
+  1 sidedata entries
+   entry-0014 size 24
+    '\x00\x00\x00\x01\x04\x00\x00\x00\x0b\x00\x00\x00\x00unrelated-l'
+  added      : unrelated-l, ;
+  ##### revision 44 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 45 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 46 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
+  ##### revision 47 #####
+  1 sidedata entries
+   entry-0014 size 4
+    '\x00\x00\x00\x00'
 
 #endif
 
@@ -1999,3 +2110,61 b' The result from mEAm is the same for the'
     a (known-bad-output upgraded !)
 
 
+Subcase: chaining salvage information during a merge
+````````````````````````````````````````````````````
+
+We add more change on the branch were the file was deleted. merging again
+should preserve the fact eh file was salvaged.
+
+reference output:
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCB-revert-m-0")'
+  M b
+  A d
+    a (filelog !)
+    a (sidedata !)
+    a (upgraded !)
+  R a
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBC-revert-m-0")'
+  M b
+  A d
+    a (filelog !)
+    a (sidedata !)
+    a (upgraded !)
+  R a
+
+chained output
+
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBC+revert,Lm")'
+  M b
+  A d
+    a (filelog !)
+    a (missing-correct-output sidedata !)
+    a (missing-correct-output upgraded !)
+  A unrelated-l
+  R a
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mCB+revert,Lm")'
+  M b
+  A d
+    a (filelog !)
+    a (missing-correct-output sidedata !)
+    a (missing-correct-output upgraded !)
+  A unrelated-l
+  R a
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mL,BC+revertm")'
+  M b
+  A d
+    a (filelog !)
+    a (missing-correct-output sidedata !)
+    a (missing-correct-output upgraded !)
+  A unrelated-l
+  R a
+  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mL,CB+revertm")'
+  M b
+  A d
+    a (filelog !)
+    a (missing-correct-output sidedata !)
+    a (missing-correct-output upgraded !)
+  A unrelated-l
+  R a
+