tests/test-copies-chain-merge.t

rust-status: add bare `hg status` support in hg-core

A lot of performance remains to be gained, most notably by doing more things
in parallel, but also by caching, not falling back to Python but switching
to another regex engine, etc..

I have measured on multiple repositories that this change, when in combination
with the next two patches, improve bare `hg status` performance, and has no
observable impact when falling back (because it does so early).

On the Netbeans repository:
C: 840ms
Rust+C: 556ms

Mozilla Central with the one pattern that causes a fallback removed:
C: 2.315s
Rust+C: 1.700 s

Differential Revision: https://phab.mercurial-scm.org/D7929

=====================================================
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
  > [ui]
  > logtemplate={rev} {desc}]\n
  > EOF

  $ hg init repo-chain
  $ cd repo-chain

Add some linear rename initialy

  $ touch a b 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]
  


Merge the two branches we just defined (in both directions)
- one with change to an unrelated file
- one with renames in them

  $ hg up 'desc("b-1")'
  0 files updated, 0 files merged, 0 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"))'
  @    7 mABm-0 simple merge - the other way]
  |\
  +---o  6 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]
  

Create a branch that delete a file previous renamed

  $ hg up 'desc("i-2")'
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg rm d
  $ hg ci -m 'c-1 delete d'
  created new head
  $ hg log -G --rev '::.'
  @  8 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]
  

Merge:
- one with change to an unrelated file
- one deleting the change
and recreate an unrelated file after the merge

  $ hg up 'desc("b-1")'
  2 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 '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"))'
  @  12 mCBm-1 re-add d]
  |
  o    11 mCBm-0 simple merge - the other way]
  |\
  | | o  10 mBCm-1 re-add d]
  | | |
  +---o  9 mBCm-0 simple merge - one way]
  | |/
  | o  8 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]
  

Create a branch that delete a file previous renamed and recreate it

  $ hg up 'desc("i-2")'
  2 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 '::.'
  @  14 d-2 re-add d]
  |
  o  13 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 an unrelated file
- one deleting and recreating the file

Note:
| In this case, the merge get conflicting information since on one side we have
| a "brand new" d. and one the other one we have "d renamed from c (itself
| renamed from c)".
|
| The current code arbitrarily pick one side

  $ hg up 'desc("b-1")'
  2 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")'
  2 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"))'
  @    16 mDBm-0 simple merge - the other way]
  |\
  +---o  15 mBDm-0 simple merge - one way]
  | |/
  | o  14 d-2 re-add d]
  | |
  | o  13 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]
  

Having another branch renaming a different file to the same filename as another

  $ hg up 'desc("i-2")'
  2 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 '::.'
  @  18 e-2 g -move-> f]
  |
  o  17 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]
  

Merge:
- 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")'
  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")'
  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  18 e-2 g -move-> f]
  | |
  | o  17 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]
  

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 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 01c2f5eabdc4 000000000000 000000000000
       1      10 b004912a8510 000000000000 000000000000
       2      15 0bb5445dc4d0 01c2f5eabdc4 b004912a8510
       3      22 c72365ee036f 000000000000 000000000000
  $ 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")'
  2 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

  $ 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 |  14 d-2 re-add d]
  | |
  o |  13 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)

  $ 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
  0 files updated, 1 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
  0 files updated, 1 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]
  


Check results
=============

merging with unrelated change does not interfer wit the renames
---------------------------------------------------------------

- rename on one side
- unrelated change on the other side

  $ 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

checks:
- 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

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.

  $ 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
  M d
  $ 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'
  0bb5445dc4d02f4e0d86cf16f9f3a411d0f17744 644   d
  $ hg manifest --debug --rev 'desc("mDBm-0")' | grep '644   d'
  b004912a8510032a0350a74daa2803dadfb00e12 644   d

The 0bb5445dc4d02f4e0d86cf16f9f3a411d0f17744 entry is wrong, since the file was
deleted on one side (then recreate) and untouched on the other side, no "merge"
has happened. The resulting `d` file is the untouched version from branch `D`,
not a merge.

  $ hg manifest --debug --rev 'desc("d-2")' | grep '644   d'
  b004912a8510032a0350a74daa2803dadfb00e12 644   d
  $ hg manifest --debug --rev 'desc("b-1")' | grep '644   d'
  01c2f5eabdc4ce2bdee42b5f86311955e6c8f573 644   d
  $ hg debugindex d
     rev linkrev nodeid       p1           p2
       0       2 01c2f5eabdc4 000000000000 000000000000
       1      10 b004912a8510 000000000000 000000000000
       2      15 0bb5445dc4d0 01c2f5eabdc4 b004912a8510
       3      22 c72365ee036f 000000000000 000000000000
       4      23 863d9bc49190 01c2f5eabdc4 c72365ee036f
       5      25 7bded9d9da1f 01c2f5eabdc4 000000000000
       6      26 f04cac32d703 b004912a8510 7bded9d9da1f
       7      27 d7a5eafb9322 7bded9d9da1f b004912a8510
       8      28 2ed7a51aed47 c72365ee036f 7bded9d9da1f

(This `hg log` output if wrong, since no merge actually happened).

  $ hg log -Gfr 'desc("mBDm-0")' d
  o    15 mBDm-0 simple merge - one way]
  |\
  o :  14 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]
  

This `hg log` output is correct

  $ hg log -Gfr 'desc("mDBm-0")' d
  o  14 d-2 re-add d]
  |
  ~

  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBDm-0")'
  M b
  A d
    a
  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 manifest --debug --rev 'desc("mAEm-0")' | grep '644   f'
  eb806e34ef6be4c264effd5933d31004ad15a793 644   f
  $ hg manifest --debug --rev 'desc("mEAm-0")' | grep '644   f'
  eb806e34ef6be4c264effd5933d31004ad15a793 644   f
  $ hg manifest --debug --rev 'desc("a-2")' | grep '644   f'
  0dd616bc7ab1a111921d95d76f69cda5c2ac539c 644   f
  $ hg manifest --debug --rev 'desc("e-2")' | grep '644   f'
  6da5a2eecb9c833f830b67a4972366d49a9a142c 644   f
  $ hg debugindex f
     rev linkrev nodeid       p1           p2
       0       4 0dd616bc7ab1 000000000000 000000000000
       1      18 6da5a2eecb9c 000000000000 000000000000
       2      19 eb806e34ef6b 0dd616bc7ab1 6da5a2eecb9c
  $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mAEm-0")'
  M f
  R b
  $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mEAm-0")'
  M f
  R b
  $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mAEm-0")'
  M f
  R d
  $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mEAm-0")'
  M f
  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
  $ 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
  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
  R a
  R b

Merge:
- one with change to an unrelated file (b)
- one overwriting a file (d) with a rename (from h to i to d)

The overwriting should take over. However, the behavior is currently buggy

  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mBFm-0")'
  M b
  A d
    a (true !)
    h (false !)
  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
  R h
  $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mBFm-0")'
  M b
  M d
  $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mBFm-0")'
  M b
  M d
  R i
  $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mFBm-0")'
  M d
  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
  R i

The following graphlog is wrong, the "a -> c -> d" chain was overwritten and should not appear.

  $ hg log -Gfr 'desc("mBFm-0")' d
  o    23 mBFm-0 simple merge - one way]
  |\
  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]
  

The following output is correct.

  $ 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]
  

Merge:
- one with change to a file
- one deleting and recreating the file

Unlike in the 'BD/DB' cases, an actuall merge happened here. So we should
consider history and rename on both branch of the merge.

  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mDGm-0")'
  A d
    a
  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

  $ hg log -Gfr 'desc("mDGm-0")' d
  o    26 mDGm-0 simple merge - one way]
  |\
  | o  25 g-1: update d]
  | |
  o |  14 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]
  


  $ hg log -Gfr 'desc("mDGm-0")' d
  o    26 mDGm-0 simple merge - one way]
  |\
  | o  25 g-1: update d]
  | |
  o |  14 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]
  


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 status --copies --rev 'desc("i-0")' --rev 'desc("mFGm-0")'
  A d
    a
  R a
  R h
  $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mGFm-0")'
  A d
    a
  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
  R i
  $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mGFm-0")'
  M d
  R i
  $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mFGm-0")'
  M d
  R h
  $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mGFm-0")'
  M d
  R h

  $ 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]
  


  $ hg log -Gfr 'desc("mGFm-0")' d
  @    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]