view tests/test-backout.t @ 35428:71427ff1dff8

workers: handling exceptions in windows workers

This adds handling of exceptions from worker threads and resurfaces them as if the function ran without workers.
If any of the threads throws, the main thread kills all running threads giving them 5 sec to handle the interruption and raises the first exception received.

We don't have to join threads if is_alive() is false

Test Plan:
Ran multiple updates/enable/disable sparse profile and things worked well

Ran test on CentOS- all tests passing on @ passed here

Added a forged exception into the worker code and got it properly resurfaced and the rest of workers killed: P58642088
PS C:\open\<repo>> ..\facebook-hg-rpms\build\hg\hg.exe --config extensions.fsmonitor=! sparse --enable-profile <profile>
updating [==>                                                                                                                ]  1300/39166 1m57sException in thread Thread-3:
Traceback (most recent call last):
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\threading.py", line 801, in __bootstrap_inner
    self.run()
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\worker.py", line 244, in run
    raise e
Exception: Forged exception

Exception in thread Thread-2:
Traceback (most recent call last):
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\threading.py", line 801, in __bootstrap_inner
    self.run()
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\worker.py", line 244, in run
    raise e
Exception: Forged exception
<...>
Traceback (most recent call last):
  File "C:\open\facebook-hg-rpms\build\hg\hgexe.py", line 41, in <module>
    dispatch.run()
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 85, in run
    status = (dispatch(req) or 0) & 255
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 173, in dispatch
    ret = _runcatch(req)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 324, in _runcatch
    return _callcatch(ui, _runcatchfunc)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 332, in _callcatch
    return scmutil.callcatch(ui, func)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\scmutil.py", line 154, in callcatch
    return func()
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 314, in _runcatchfunc
    return _dispatch(req)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 951, in _dispatch
    cmdpats, cmdoptions)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\remotefilelog\__init__.py", line 415, in runcommand
    return orig(lui, repo, *args, **kwargs)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\undo.py", line 118, in _runcommandwrapper
    result = orig(lui, repo, cmd, fullargs, *args)
  File "C:\open\facebook-hg-rpms\build\hg\hgext\journal.py", line 84, in runcommand
    return orig(lui, repo, cmd, fullargs, *args)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\perftweaks.py", line 268, in _tracksparseprofiles
    res = runcommand(lui, repo, *args)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\perftweaks.py", line 256, in _trackdirstatesizes
    res = runcommand(lui, repo, *args)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\copytrace.py", line 144, in _runcommand
    return orig(lui, repo, cmd, fullargs, ui, *args, **kwargs)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\fbamend\hiddenoverride.py", line 119, in runcommand
    result = orig(lui, repo, cmd, fullargs, *args)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 712, in runcommand
    ret = _runcommand(ui, options, cmd, d)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 959, in _runcommand
    return cmdfunc()
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\dispatch.py", line 948, in <lambda>
    d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\util.py", line 1183, in check
    return func(*args, **kwargs)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\fbsparse.py", line 860, in sparse
    disableprofile=disableprofile, force=force)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\fbsparse.py", line 949, in _config
    len, _refresh(ui, repo, oldstatus, oldsparsematch, force))
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\hgext3rd\fbsparse.py", line 1116, in _refresh
    mergemod.applyupdates(repo, typeactions, repo[None], repo['.'], False)
  File "C:\open\facebook-hg-rpms\build\hg\hg-python\lib\site-packages\remotefilelog\__init__.py", line 311, in applyupdates
    return orig(repo, actions, wctx, mctx, overwrite, labels=labels)
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\merge.py", line 1464, in applyupdates
    for i, item in prog:
  File "C:\open\facebook-hg-rpms\build\hg\mercurial\worker.py", line 286, in _windowsworker
    raise t.exception
Exception: Forged exception
PS C:\open\ovrsource>

Differential Revision: https://phab.mercurial-scm.org/D1459

  $ hg init basic
  $ cd basic

should complain

  $ hg backout
  abort: please specify a revision to backout
  [255]
  $ hg backout -r 0 0
  abort: please specify just one revision
  [255]

basic operation
(this also tests that editor is invoked if the commit message is not
specified explicitly)

  $ echo a > a
  $ hg commit -d '0 0' -A -m a
  adding a
  $ echo b >> a
  $ hg commit -d '1 0' -m b

  $ hg status --rev tip --rev "tip^1"
  M a
  $ HGEDITOR=cat hg backout -d '2 0' tip --tool=true
  reverting a
  Backed out changeset a820f4f40a57
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: changed a
  changeset 2:2929462c3dff backs out changeset 1:a820f4f40a57
  $ cat a
  a
  $ hg summary
  parent: 2:2929462c3dff tip
   Backed out changeset a820f4f40a57
  branch: default
  commit: (clean)
  update: (current)
  phases: 3 draft

commit option

  $ cd ..
  $ hg init commit
  $ cd commit

  $ echo tomatoes > a
  $ hg add a
  $ hg commit -d '0 0' -m tomatoes

  $ echo chair > b
  $ hg add b
  $ hg commit -d '1 0' -m chair

  $ echo grapes >> a
  $ hg commit -d '2 0' -m grapes

  $ hg backout -d '4 0' 1 --tool=:fail
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  changeset 3:1c2161e97c0a backs out changeset 1:22cb4f70d813
  $ hg summary
  parent: 3:1c2161e97c0a tip
   Backed out changeset 22cb4f70d813
  branch: default
  commit: (clean)
  update: (current)
  phases: 4 draft

  $ echo ypples > a
  $ hg commit -d '5 0' -m ypples

  $ hg backout -d '6 0' 2 --tool=:fail
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]
  $ hg summary
  parent: 4:ed99997b793d tip
   ypples
  branch: default
  commit: 1 unresolved (clean)
  update: (current)
  phases: 5 draft

file that was removed is recreated
(this also tests that editor is not invoked if the commit message is
specified explicitly)

  $ cd ..
  $ hg init remove
  $ cd remove

  $ echo content > a
  $ hg commit -d '0 0' -A -m a
  adding a

  $ hg rm a
  $ hg commit -d '1 0' -m b

  $ HGEDITOR=cat hg backout -d '2 0' tip --tool=true -m "Backed out changeset 76862dcce372"
  adding a
  changeset 2:de31bdc76c0d backs out changeset 1:76862dcce372
  $ cat a
  content
  $ hg summary
  parent: 2:de31bdc76c0d tip
   Backed out changeset 76862dcce372
  branch: default
  commit: (clean)
  update: (current)
  phases: 3 draft

backout of backout is as if nothing happened

  $ hg backout -d '3 0' --merge tip --tool=true
  removing a
  changeset 3:7f6d0f120113 backs out changeset 2:de31bdc76c0d
  $ test -f a
  [1]
  $ hg summary
  parent: 3:7f6d0f120113 tip
   Backed out changeset de31bdc76c0d
  branch: default
  commit: (clean)
  update: (current)
  phases: 4 draft

Test that 'hg rollback' restores dirstate just before opening
transaction: in-memory dirstate changes should be written into
'.hg/journal.dirstate' as expected.

  $ echo 'removed soon' > b
  $ hg commit -A -d '4 0' -m 'prepare for subsequent removing'
  adding b
  $ echo 'newly added' > c
  $ hg add c
  $ hg remove b
  $ hg commit -d '5 0' -m 'prepare for subsequent backout'
  $ touch -t 200001010000 c
  $ hg status -A
  C c
  $ hg debugstate --nodates
  n 644         12 set                 c
  $ hg backout -d '6 0' -m 'to be rollback-ed soon' -r .
  adding b
  removing c
  changeset 6:4bfec048029d backs out changeset 5:fac0b729a654
  $ hg rollback -q
  $ hg status -A
  A b
  R c
  $ hg debugstate --nodates
  a   0         -1 unset               b
  r   0          0 set                 c

across branch

  $ cd ..
  $ hg init branch
  $ cd branch
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ echo b > b
  $ hg ci -Am1
  adding b
  $ hg co -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg summary
  parent: 0:f7b1eb17ad24 
   0
  branch: default
  commit: (clean)
  update: 1 new changesets (update)
  phases: 2 draft

should fail

  $ hg backout 1
  abort: cannot backout change that is not an ancestor
  [255]
  $ echo c > c
  $ hg ci -Am2
  adding c
  created new head
  $ hg summary
  parent: 2:db815d6d32e6 tip
   2
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 3 draft

should fail

  $ hg backout 1
  abort: cannot backout change that is not an ancestor
  [255]
  $ hg summary
  parent: 2:db815d6d32e6 tip
   2
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 3 draft

backout with merge

  $ cd ..
  $ hg init merge
  $ cd merge

  $ echo line 1 > a
  $ echo line 2 >> a
  $ hg commit -d '0 0' -A -m a
  adding a
  $ hg summary
  parent: 0:59395513a13a tip
   a
  branch: default
  commit: (clean)
  update: (current)
  phases: 1 draft

remove line 1

  $ echo line 2 > a
  $ hg commit -d '1 0' -m b

  $ echo line 3 >> a
  $ hg commit -d '2 0' -m c

  $ hg backout --merge -d '3 0' 1 --tool=true
  reverting a
  created new head
  changeset 3:26b8ccb9ad91 backs out changeset 1:5a50a024c182
  merging with changeset 3:26b8ccb9ad91
  merging a
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -d '4 0' -m d
  $ hg summary
  parent: 4:c7df5e0b9c09 tip
   d
  branch: default
  commit: (clean)
  update: (current)
  phases: 5 draft

check line 1 is back

  $ cat a
  line 1
  line 2
  line 3

Test visibility of in-memory dirstate changes outside transaction to
external hook process

  $ cat > $TESTTMP/checkvisibility.sh <<EOF
  > echo "==== \$1:"
  > hg parents --template "{rev}:{node|short}\n"
  > echo "===="
  > EOF

"hg backout --merge REV1" at REV2 below implies steps below:

(1) update to REV1 (REV2 => REV1)
(2) revert by REV1^1
(3) commit backing out revision (REV3)
(4) update to REV2 (REV3 => REV2)
(5) merge with REV3 (REV2 => REV2, REV3)

== test visibility to external preupdate hook

  $ hg update -q -C 2
  $ hg --config extensions.strip= strip 3
  saved backup bundle to * (glob)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > preupdate.visibility = sh $TESTTMP/checkvisibility.sh preupdate
  > EOF

("-m" is needed to avoid writing dirstate changes out at other than
invocation of the hook to be examined)

  $ hg backout --merge -d '3 0' 1 --tool=true -m 'fixed comment'
  ==== preupdate:
  2:6ea3f2a197a2
  ====
  reverting a
  created new head
  changeset 3:d92a3f57f067 backs out changeset 1:5a50a024c182
  ==== preupdate:
  3:d92a3f57f067
  ====
  merging with changeset 3:d92a3f57f067
  ==== preupdate:
  2:6ea3f2a197a2
  ====
  merging a
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > preupdate.visibility =
  > EOF

== test visibility to external update hook

  $ hg update -q -C 2
  $ hg --config extensions.strip= strip 3
  saved backup bundle to * (glob)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > update.visibility = sh $TESTTMP/checkvisibility.sh update
  > EOF

  $ hg backout --merge -d '3 0' 1 --tool=true -m 'fixed comment'
  ==== update:
  1:5a50a024c182
  ====
  reverting a
  created new head
  changeset 3:d92a3f57f067 backs out changeset 1:5a50a024c182
  ==== update:
  2:6ea3f2a197a2
  ====
  merging with changeset 3:d92a3f57f067
  merging a
  ==== update:
  2:6ea3f2a197a2
  3:d92a3f57f067
  ====
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > update.visibility =
  > EOF

  $ cd ..

backout should not back out subsequent changesets

  $ hg init onecs
  $ cd onecs
  $ echo 1 > a
  $ hg commit -d '0 0' -A -m a
  adding a
  $ echo 2 >> a
  $ hg commit -d '1 0' -m b
  $ echo 1 > b
  $ hg commit -d '2 0' -A -m c
  adding b
  $ hg summary
  parent: 2:882396649954 tip
   c
  branch: default
  commit: (clean)
  update: (current)
  phases: 3 draft

without --merge
  $ hg backout --no-commit -d '3 0' 1 --tool=true
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  changeset 22bca4c721e5 backed out, don't forget to commit.
  $ hg locate b
  b
  $ hg update -C tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg locate b
  b
  $ hg summary
  parent: 2:882396649954 tip
   c
  branch: default
  commit: (clean)
  update: (current)
  phases: 3 draft

with --merge
  $ hg backout --merge -d '3 0' 1 --tool=true
  reverting a
  created new head
  changeset 3:3202beb76721 backs out changeset 1:22bca4c721e5
  merging with changeset 3:3202beb76721
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg locate b
  b
  $ hg update -C tip
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg locate b
  [1]

  $ cd ..
  $ hg init m
  $ cd m
  $ echo a > a
  $ hg commit -d '0 0' -A -m a
  adding a
  $ echo b > b
  $ hg commit -d '1 0' -A -m b
  adding b
  $ echo c > c
  $ hg commit -d '2 0' -A -m b
  adding c
  $ hg update 1
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo d > d
  $ hg commit -d '3 0' -A -m c
  adding d
  created new head
  $ hg merge 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -d '4 0' -A -m d
  $ hg summary
  parent: 4:b2f3bb92043e tip
   d
  branch: default
  commit: (clean)
  update: (current)
  phases: 5 draft

backout of merge should fail

  $ hg backout 4
  abort: cannot backout a merge changeset
  [255]

backout of merge with bad parent should fail

  $ hg backout --parent 0 4
  abort: cb9a9f314b8b is not a parent of b2f3bb92043e
  [255]

backout of non-merge with parent should fail

  $ hg backout --parent 0 3
  abort: cannot use --parent on non-merge changeset
  [255]

backout with valid parent should be ok

  $ hg backout -d '5 0' --parent 2 4 --tool=true
  removing d
  changeset 5:10e5328c8435 backs out changeset 4:b2f3bb92043e
  $ hg summary
  parent: 5:10e5328c8435 tip
   Backed out changeset b2f3bb92043e
  branch: default
  commit: (clean)
  update: (current)
  phases: 6 draft

  $ hg rollback
  repository tip rolled back to revision 4 (undo commit)
  working directory now based on revision 4
  $ hg update -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg summary
  parent: 4:b2f3bb92043e tip
   d
  branch: default
  commit: (clean)
  update: (current)
  phases: 5 draft

  $ hg backout -d '6 0' --parent 3 4 --tool=true
  removing c
  changeset 5:033590168430 backs out changeset 4:b2f3bb92043e
  $ hg summary
  parent: 5:033590168430 tip
   Backed out changeset b2f3bb92043e
  branch: default
  commit: (clean)
  update: (current)
  phases: 6 draft

  $ cd ..

named branches

  $ hg init named_branches
  $ cd named_branches

  $ echo default > default
  $ hg ci -d '0 0' -Am default
  adding default
  $ hg branch branch1
  marked working directory as branch branch1
  (branches are permanent and global, did you want a bookmark?)
  $ echo branch1 > file1
  $ hg ci -d '1 0' -Am file1
  adding file1
  $ hg branch branch2
  marked working directory as branch branch2
  $ echo branch2 > file2
  $ hg ci -d '2 0' -Am file2
  adding file2

without --merge
  $ hg backout --no-commit -r 1 --tool=true
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  changeset bf1602f437f3 backed out, don't forget to commit.
  $ hg branch
  branch2
  $ hg status -A
  R file1
  C default
  C file2
  $ hg summary
  parent: 2:45bbcd363bf0 tip
   file2
  branch: branch2
  commit: 1 removed
  update: (current)
  phases: 3 draft

with --merge
(this also tests that editor is invoked if '--edit' is specified
explicitly regardless of '--message')

  $ hg update -qC
  $ HGEDITOR=cat hg backout --merge -d '3 0' -r 1 -m 'backout on branch1' --tool=true --edit
  removing file1
  backout on branch1
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'branch2'
  HG: removed file1
  created new head
  changeset 3:d4e8f6db59fb backs out changeset 1:bf1602f437f3
  merging with changeset 3:d4e8f6db59fb
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg summary
  parent: 2:45bbcd363bf0 
   file2
  parent: 3:d4e8f6db59fb tip
   backout on branch1
  branch: branch2
  commit: 1 removed (merge)
  update: (current)
  phases: 4 draft
  $ hg update -q -C 2

on branch2 with branch1 not merged, so file1 should still exist:

  $ hg id
  45bbcd363bf0 (branch2)
  $ hg st -A
  C default
  C file1
  C file2
  $ hg summary
  parent: 2:45bbcd363bf0 
   file2
  branch: branch2
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 4 draft

on branch2 with branch1 merged, so file1 should be gone:

  $ hg merge
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -d '4 0' -m 'merge backout of branch1'
  $ hg id
  22149cdde76d (branch2) tip
  $ hg st -A
  C default
  C file2
  $ hg summary
  parent: 4:22149cdde76d tip
   merge backout of branch1
  branch: branch2
  commit: (clean)
  update: (current)
  phases: 5 draft

on branch1, so no file1 and file2:

  $ hg co -C branch1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg id
  bf1602f437f3 (branch1)
  $ hg st -A
  C default
  C file1
  $ hg summary
  parent: 1:bf1602f437f3 
   file1
  branch: branch1
  commit: (clean)
  update: (current)
  phases: 5 draft

  $ cd ..

backout of empty changeset (issue4190)

  $ hg init emptycommit
  $ cd emptycommit

  $ touch file1
  $ hg ci -Aqm file1
  $ hg branch -q branch1
  $ hg ci -qm branch1
  $ hg backout -v 1
  resolving manifests
  nothing changed
  [1]

  $ cd ..


Test usage of `hg resolve` in case of conflict
(issue4163)

  $ hg init issue4163
  $ cd issue4163
  $ touch foo
  $ hg add foo
  $ cat > foo << EOF
  > one
  > two
  > three
  > four
  > five
  > six
  > seven
  > height
  > nine
  > ten
  > EOF
  $ hg ci -m 'initial'
  $ cat > foo << EOF
  > one
  > two
  > THREE
  > four
  > five
  > six
  > seven
  > height
  > nine
  > ten
  > EOF
  $ hg ci -m 'capital three'
  $ cat > foo << EOF
  > one
  > two
  > THREE
  > four
  > five
  > six
  > seven
  > height
  > nine
  > TEN
  > EOF
  $ hg ci -m 'capital ten'
  $ hg backout -r 'desc("capital three")' --tool internal:fail
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]
  $ hg status
  $ hg debugmergestate
  * version 2 records
  local: b71750c4b0fdf719734971e3ef90dbeab5919a2d
  other: a30dd8addae3ce71b8667868478542bc417439e6
  file extras: foo (ancestorlinknode = 91360952243723bd5b1138d5f26bd8c8564cb553)
  file: foo (record type "F", state "u", hash 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33)
    local path: foo (flags "")
    ancestor path: foo (node f89532f44c247a0e993d63e3a734dd781ab04708)
    other path: foo (node f50039b486d6fa1a90ae51778388cad161f425ee)
  $ mv .hg/merge/state2 .hg/merge/state2-moved
  $ hg debugmergestate
  * version 1 records
  local: b71750c4b0fdf719734971e3ef90dbeab5919a2d
  file: foo (record type "F", state "u", hash 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33)
    local path: foo (flags "")
    ancestor path: foo (node f89532f44c247a0e993d63e3a734dd781ab04708)
    other path: foo (node not stored in v1 format)
  $ mv .hg/merge/state2-moved .hg/merge/state2
  $ hg resolve -l  # still unresolved
  U foo
  $ hg summary
  parent: 2:b71750c4b0fd tip
   capital ten
  branch: default
  commit: 1 unresolved (clean)
  update: (current)
  phases: 3 draft
  $ hg resolve --all --debug
  picked tool ':merge' for foo (binary False symlink False changedelete False)
  merging foo
  my foo@b71750c4b0fd+ other foo@a30dd8addae3 ancestor foo@913609522437
   premerge successful
  (no more unresolved files)
  continue: hg commit
  $ hg status
  M foo
  ? foo.orig
  $ hg resolve -l
  R foo
  $ hg summary
  parent: 2:b71750c4b0fd tip
   capital ten
  branch: default
  commit: 1 modified, 1 unknown
  update: (current)
  phases: 3 draft
  $ cat foo
  one
  two
  three
  four
  five
  six
  seven
  height
  nine
  TEN

--no-commit shouldn't commit

  $ hg init a
  $ cd a
  $ for i in 1 2 3; do
  >   touch $i
  >   hg ci -Am $i
  > done
  adding 1
  adding 2
  adding 3
  $ hg backout --no-commit .
  removing 3
  changeset cccc23d9d68f backed out, don't forget to commit.
  $ hg revert -aq

--no-commit can't be used with --merge

  $ hg backout --merge --no-commit 2
  abort: cannot use --merge with --no-commit
  [255]