view tests/test-branches.t @ 25759:ff11c1565c04

cmdutil: apply dirstate.normallookup on (maybe partially) committed files

To detect change of a file without redundant comparison of file
content, dirstate recognizes a file as certainly clean, if:

  (1) it is already known as "normal",
  (2) dirstate entry for it has valid (= not "-1") timestamp, and
  (3) mode, size and timestamp of it on the filesystem are as same as
      ones expected in dirstate

This works as expected in many cases, but doesn't in the corner case
that changing a file keeps mode, size and timestamp of it on the
filesystem.

The timetable below shows steps in one of typical such situations:

  ---- ----------------------------------- ----------------
                                           timestamp of "f"
                                           ----------------
                                           dirstate   file-
  time          action                     mem  file  system
  ---- ----------------------------------- ---- ----- -----
  N                                              ***   ***
       - change "f"                                     N

       - execute 'hg commit -i'
         - backup "f" with timestamp N
         - revert "f" by 'merge.update()'               N
           with 'partially'
         - apply selected hunks                         N
           by 'patch.patch()'

         - 'repo.commit()'
           - 'dirstate.normal("f")'         N
  N+1
           - 'dirstate.write()'             N    N

         - restore "f"                                  N+1
         - restore timestamp of "f"                     N

       - 'hg status' shows "f" as "clean"   N    N      N
  ---- ----------------------------------- ---- ----- -----

The most important point is that 'dirstate.write()' is executed at N+1
or later. This causes writing dirstate timestamp N of "f" out
successfully. If it is executed at N, 'parsers.pack_dirstate()'
replaces timestamp N with "-1" before actual writing dirstate out.

This issue can occur when 'hg commit -i' satisfies conditions below:

  - the file is committed partially, and
  - mode and size of the file aren't changed before and after committing

The root cause of this issue is that (maybe partially changed) files
are restored with original timestamp but dirstate isn't updated for
them.

To detect changes of files correctly, this patch applies
'dirstate.normallookup()' on restored files. Status check is needed
before 'dirstate.normallookup()', because status other than "n(ormal)"
should be kept at failure of committing.

This patch doesn't examine whether each files are committed fully or
partially, because interactive hunk selection makes it difficult.

After this change, timetable is changed as below:

  ---- ----------------------------------- ----------------
                                           timestamp of "f"
                                           ----------------
                                           dirstate   file-
  time          action                     mem  file  system
  ---- ----------------------------------- ---- ----- -----
  N                                              ***   ***
       - change "f"                                     N

       - execute 'hg commit -i'
         - backup "f" with timestamp N
         - revert "f" by 'merge.update()'               N
           with 'partially'
         - apply selected hunks                         N
           by 'patch.internalpatch()'

         - 'repo.commit()'
           - 'dirstate.normal("f")'         N
  N+1
           - 'dirstate.write()'             N    N

         - restore "f"                                  N+1
         - restore timestamp of "f"                     N
       ----------------------------------- ---- ----- -----
         - normallookup("f")                -1
         - release wlock
           - 'dirstate.write()'             -1   -1     N
       ----------------------------------- ---- ----- -----

       - 'hg status' shows "f" as "clean"   -1   -1     N
  ---- ----------------------------------- ---- ----- -----

To reproduce this issue in tests certainly, this patch emulates some
timing critical actions as below:

  - change "f" at N

    'touch -t 200001010000' before command invocation changes mtime of
    "f" to "2000-01-01 00:00" (= N).

  - apply selected hunks at N

    'patch.internalpatch()' with 'fakepatchtime.py' explicitly changes
    mtime of patched files to "2000-01-01 00:00" (= N).

  - 'dirstate.write()' at N+1 (or "not at N")

    'pack_dirstate()' uses actual timestamp at runtime as "now", and
    it should be different from the "2000-01-01 00:00" of "f".

BTW, in 'test-commit-interactive.t', files are sometimes treated as
modified , even though they are just committed fully via 'hg commit
-i' and 'hg diff' shows nothing for them.

Enabling win32text causes EOL style mismatching below:

  - files are changed in LF style EOL

    => files restored after committing uses LF style EOL (1)

  - 'merge.update()' reverts files in CRLF style EOL
  - 'patch.internalpatch()' changes files in CRLF style EOL

    => 'dirstate.normal()' via 'repo.commit()' uses the size of files
       in CRLF style EOL (2)

Therefore, fully committed files are treated as "modified", because
'lstat()' returns size of (1) restored files in LF style EOL, but
dirstate expects size of (2) committed files in CRLF style EOL.

After this patch, 'dirstate.normallookup()' on committed files forces
subsequent 'hg status' to examine changes exactly, and fully committed
files are treated as clean as expected.

This is reason why this patch also does:

  - add some 'hg status' checking status of fully committed files
  - clear win32text configuration before size/timestamp sensitive examination

  $ hg init a
  $ cd a
  $ echo 'root' >root
  $ hg add root
  $ hg commit -d '0 0' -m "Adding root node"

  $ echo 'a' >a
  $ hg add a
  $ hg branch a
  marked working directory as branch a
  (branches are permanent and global, did you want a bookmark?)
  $ hg commit -d '1 0' -m "Adding a branch"

  $ hg branch q
  marked working directory as branch q
  $ echo 'aa' >a
  $ hg branch -C
  reset working directory to branch a
  $ hg commit -d '2 0' -m "Adding to a branch"

  $ hg update -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo 'b' >b
  $ hg add b
  $ hg branch b
  marked working directory as branch b
  $ hg commit -d '2 0' -m "Adding b branch"

  $ echo 'bh1' >bh1
  $ hg add bh1
  $ hg commit -d '3 0' -m "Adding b branch head 1"

  $ hg update -C 2
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo 'bh2' >bh2
  $ hg add bh2
  $ hg commit -d '4 0' -m "Adding b branch head 2"

  $ echo 'c' >c
  $ hg add c
  $ hg branch c
  marked working directory as branch c
  $ hg commit -d '5 0' -m "Adding c branch"

reserved names

  $ hg branch tip
  abort: the name 'tip' is reserved
  [255]
  $ hg branch null
  abort: the name 'null' is reserved
  [255]
  $ hg branch .
  abort: the name '.' is reserved
  [255]

invalid characters

  $ hg branch 'foo:bar'
  abort: ':' cannot be used in a name
  [255]

  $ hg branch 'foo
  > bar'
  abort: '\n' cannot be used in a name
  [255]

trailing or leading spaces should be stripped before testing duplicates

  $ hg branch 'b '
  abort: a branch of the same name already exists
  (use 'hg update' to switch to it)
  [255]

  $ hg branch ' b'
  abort: a branch of the same name already exists
  (use 'hg update' to switch to it)
  [255]

verify update will accept invalid legacy branch names

  $ hg init test-invalid-branch-name
  $ cd test-invalid-branch-name
  $ hg pull -u "$TESTDIR"/bundles/test-invalid-branch-name.hg
  pulling from *test-invalid-branch-name.hg (glob)
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg update '"colon:test"'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

  $ echo 'd' >d
  $ hg add d
  $ hg branch 'a branch name much longer than the default justification used by branches'
  marked working directory as branch a branch name much longer than the default justification used by branches
  $ hg commit -d '6 0' -m "Adding d branch"

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

-------

  $ hg branches -a
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0

--- Branch a

  $ hg log -b a
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   2:881fe2b92ad0
  branch:      a
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     Adding to a branch
  
  changeset:   1:dd6b440dd85a
  branch:      a
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     Adding a branch
  

---- Branch b

  $ hg log -b b
  changeset:   4:aee39cd168d0
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     Adding b branch head 1
  
  changeset:   3:ac22033332d1
  branch:      b
  parent:      0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     Adding b branch
  

---- going to test branch closing

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg up -C b
  2 files updated, 0 files merged, 4 files removed, 0 files unresolved
  $ echo 'xxx1' >> b
  $ hg commit -d '7 0' -m 'adding cset to branch b'
  $ hg up -C aee39cd168d0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'xxx2' >> b
  $ hg commit -d '8 0' -m 'adding head to branch b'
  created new head
  $ echo 'xxx3' >> b
  $ hg commit -d '9 0' -m 'adding another cset to branch b'
  $ hg branches
  b                             10:bfbe841b666e
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg heads --closed
  changeset:   10:bfbe841b666e
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     adding another cset to branch b
  
  changeset:   8:eebb944467c9
  branch:      b
  parent:      4:aee39cd168d0
  user:        test
  date:        Thu Jan 01 00:00:07 1970 +0000
  summary:     adding cset to branch b
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  
  $ hg heads
  changeset:   10:bfbe841b666e
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     adding another cset to branch b
  
  changeset:   8:eebb944467c9
  branch:      b
  parent:      4:aee39cd168d0
  user:        test
  date:        Thu Jan 01 00:00:07 1970 +0000
  summary:     adding cset to branch b
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  
  $ hg commit -d '9 0' --close-branch -m 'prune bad branch'
  $ hg branches -a
  b                              8:eebb944467c9
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  $ hg up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg commit -d '9 0' --close-branch -m 'close this part branch too'
  $ hg commit -d '9 0' --close-branch -m 're-closing this branch'
  abort: can only close branch heads
  [255]

  $ hg log -r tip --debug
  changeset:   12:e3d49c0575d8fc2cb1cd6859c747c14f5f6d499f
  branch:      b
  tag:         tip
  phase:       draft
  parent:      8:eebb944467c9fb9651ed232aeaf31b3c0a7fc6c1
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    8:6f9ed32d2b310e391a4f107d5f0f071df785bfee
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  extra:       branch=b
  extra:       close=1
  description:
  close this part branch too
  
  
--- b branch should be inactive

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg branches -c
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                             12:e3d49c0575d8 (closed)
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg branches -a
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  $ hg branches -q
  a branch name much longer than the default justification used by branches
  c
  a
  default
  $ hg heads b
  no open branch heads found on branches b
  [1]
  $ hg heads --closed b
  changeset:   12:e3d49c0575d8
  branch:      b
  tag:         tip
  parent:      8:eebb944467c9
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     close this part branch too
  
  changeset:   11:d3f163457ebf
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     prune bad branch
  
  $ echo 'xxx4' >> b
  $ hg commit -d '9 0' -m 'reopen branch with a change'
  reopening closed branch head 12

--- branch b is back in action

  $ hg branches -a
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57

---- test heads listings

  $ hg heads
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  

branch default

  $ hg heads default
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  

branch a

  $ hg heads a
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  $ hg heads --active a
  no open branch heads found on branches a
  [1]

branch b

  $ hg heads b
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  $ hg heads --closed b
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  changeset:   11:d3f163457ebf
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     prune bad branch
  
default branch colors:

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > color =
  > [color]
  > mode = ansi
  > EOF

  $ hg up -C c
  3 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg commit -d '9 0' --close-branch -m 'reclosing this branch'
  $ hg up -C b
  2 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg branches --color=always
  \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

default closed branch color:

  $ hg branches --color=always --closed
  \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;30;1mc\x1b[0m\x1b[0;33m                             14:f894c25619d3\x1b[0m (closed) (esc)
  \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > color =
  > [color]
  > branches.active = green
  > branches.closed = blue
  > branches.current = red
  > branches.inactive = magenta
  > log.changeset = cyan
  > EOF

custom branch colors:

  $ hg branches --color=always
  \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

custom closed branch color:

  $ hg branches --color=always --closed
  \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;34mc\x1b[0m\x1b[0;36m                             14:f894c25619d3\x1b[0m (closed) (esc)
  \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

template output:

  $ hg branches -Tjson --closed
  [
   {
    "active": true,
    "branch": "b",
    "closed": false,
    "current": true,
    "node": "e23b5505d1ad24aab6f84fd8c7cb8cd8e5e93be0",
    "rev": 13
   },
   {
    "active": true,
    "branch": "a branch name much longer than the default justification used by branches",
    "closed": false,
    "current": false,
    "node": "10ff5895aa5793bd378da574af8cec8ea408d831",
    "rev": 7
   },
   {
    "active": false,
    "branch": "c",
    "closed": true,
    "current": false,
    "node": "f894c25619d3f1484639d81be950e0a07bc6f1f6",
    "rev": 14
   },
   {
    "active": false,
    "branch": "a",
    "closed": false,
    "current": false,
    "node": "d8cbc61dbaa6dc817175d1e301eecb863f280832",
    "rev": 5
   },
   {
    "active": false,
    "branch": "default",
    "closed": false,
    "current": false,
    "node": "19709c5a4e75bf938f8e349aff97438539bb729e",
    "rev": 0
   }
  ]


Tests of revision branch name caching

We rev branch cache is updated automatically. In these tests we use a trick to
trigger rebuilds. We remove the branch head cache and run 'hg head' to cause a
rebuild that also will populate the rev branch cache.

revision branch cache is created when building the branch head cache
  $ rm -rf .hg/cache; hg head a -T '{rev}\n'
  5
  $ f --hexdump --size .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=87
  0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
  0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
  0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
  0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
  0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
  0050: 72 61 6e 63 68 65 73                            |ranches|
  .hg/cache/rbc-revs-v1: size=120
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
  0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
  0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
  0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
  0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
  0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
  0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
  0070: f8 94 c2 56 80 00 00 03                         |...V....|

#if unix-permissions no-root
no errors when revbranchcache is not writable

  $ echo >> .hg/cache/rbc-revs-v1
  $ chmod a-w .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n'
  5
  $ chmod a+w .hg/cache/rbc-revs-v1
#endif

recovery from invalid cache revs file with trailing data
  $ echo >> .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 120
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
recovery from invalid cache file with partial last record
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 119 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=119
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 112
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
recovery from invalid cache file with missing record - no truncation
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 112 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
recovery from invalid cache file with some bad records
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 8 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=8
  $ f -qDB 112 rbc-revs-v1 >> .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
  $ hg log -r 'branch(.)' -T '{rev} ' --debug
  3 4 8 9 10 11 12 13 truncating cache/rbc-revs-v1 to 8
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 104
  $ f --size --hexdump --bytes=16 .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
cache is updated when committing
  $ hg branch i-will-regret-this
  marked working directory as branch i-will-regret-this
  $ hg ci -m regrets
  $ f --size .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=106
  .hg/cache/rbc-revs-v1: size=128
update after rollback - the cache will be correct but rbc-names will will still
contain the branch name even though it no longer is used
  $ hg up -qr '.^'
  $ hg rollback -qf
  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=106
  0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
  0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
  0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
  0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
  0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
  0050: 72 61 6e 63 68 65 73 00 69 2d 77 69 6c 6c 2d 72 |ranches.i-will-r|
  0060: 65 67 72 65 74 2d 74 68 69 73                   |egret-this|
  .hg/cache/rbc-revs-v1: size=120
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
  0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
  0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
  0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
  0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
  0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
  0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
  0070: f8 94 c2 56 80 00 00 03                         |...V....|
cache is updated/truncated when stripping - it is thus very hard to get in a
situation where the cache is out of sync and the hash check detects it
  $ hg --config extensions.strip= strip -r tip --nob
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=112

  $ cd ..