view tests/test-merge-tools.t @ 23787:678f53865c68

revset: use localrepo revbranchcache for branch name filtering

Branch name filtering in revsets was expensive. For every rev it created a
changectx and called .branch() which retrieved the branch name from the
changelog.

Instead, use the revbranchcache.

The revbranchcache is used read-only. The revset implementation with generators
and callbacks makes it hard to figure out when we are done using/updating the
cache and could write it back. It would also be 'tricky' to lock the repo for
writing from within a revset execution. Finally, the branchmap update will
usually make sure that the cache is updated before any revset can be run.
The revbranchcache is used without any locking but is short-lived and used in a
tight loop where we can assume that the changelog doesn't change ... or where
it not is relevant to us if it does.

perfrevset 'branch(mobile)' on mozilla-central.
Before:
! wall 10.989637 comb 10.970000 user 10.940000 sys 0.030000 (best of 3)
After, no cache:
! wall 7.368656 comb 7.370000 user 7.360000 sys 0.010000 (best of 3)
After, with cache:
! wall 0.528098 comb 0.530000 user 0.530000 sys 0.000000 (best of 18)

The performance improvement even without cache come from being based on
branchinfo on the changelog instead of using ctx.branch().

Some tests are added to verify that the revbranchcache works and keep an eye on
when the cache files actually are updated.

test merge-tools configuration - mostly exercising filemerge.py

  $ unset HGMERGE # make sure HGMERGE doesn't interfere with the test
  $ hg init

revision 0

  $ echo "revision 0" > f
  $ echo "space" >> f
  $ hg commit -Am "revision 0"
  adding f

revision 1

  $ echo "revision 1" > f
  $ echo "space" >> f
  $ hg commit -Am "revision 1"
  $ hg update 0 > /dev/null

revision 2

  $ echo "revision 2" > f
  $ echo "space" >> f
  $ hg commit -Am "revision 2"
  created new head
  $ hg update 0 > /dev/null

revision 3 - simple to merge

  $ echo "revision 3" >> f
  $ hg commit -Am "revision 3"
  created new head

revision 4 - hard to merge

  $ hg update 0 > /dev/null
  $ echo "revision 4" > f
  $ hg commit -Am "revision 4"
  created new head

  $ echo "[merge-tools]" > .hg/hgrc

  $ beforemerge() {
  >   cat .hg/hgrc
  >   echo "# hg update -C 1"
  >   hg update -C 1 > /dev/null
  > }
  $ aftermerge() {
  >   echo "# cat f"
  >   cat f
  >   echo "# hg stat"
  >   hg stat
  >   rm -f f.orig
  > }

Tool selection

default is internal merge:

  $ beforemerge
  [merge-tools]
  # hg update -C 1

hg merge -r 2
override $PATH to ensure hgmerge not visible; use $PYTHON in case we're
running from a devel copy, not a temp installation

  $ PATH="$BINDIR" $PYTHON "$BINDIR"/hg merge -r 2
  merging f
  warning: conflicts during merge.
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  <<<<<<< local: ef83787e2614  - test: revision 1
  revision 1
  =======
  revision 2
  >>>>>>> other: 0185f4e0cf02  - test: revision 2
  space
  # hg stat
  M f
  ? f.orig

simplest hgrc using false for merge:

  $ echo "false.whatever=" >> .hg/hgrc
  $ beforemerge
  [merge-tools]
  false.whatever=
  # hg update -C 1
  $ hg merge -r 2
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

unexecutable file in $PATH shouldn't be found:

  $ touch false
  $ hg up -qC 1
  $ PATH="`pwd`:$BINDIR" $PYTHON "$BINDIR"/hg merge -r 2
  merging f
  warning: conflicts during merge.
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ rm false

executable directory in $PATH shouldn't be found:

  $ mkdir false
  $ hg up -qC 1
  $ PATH="`pwd`:$BINDIR" $PYTHON "$BINDIR"/hg merge -r 2
  merging f
  warning: conflicts during merge.
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ rmdir false

true with higher .priority gets precedence:

  $ echo "true.priority=1" >> .hg/hgrc
  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  # hg update -C 1
  $ hg merge -r 2
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

unless lowered on command line:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.priority=-7
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

or false set higher on command line:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.false.priority=117
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

or true.executable not found in PATH:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=nonexistentmergetool
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

or true.executable with bogus path:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=/nonexistent/mergetool
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

but true.executable set to cat found in PATH works:

  $ echo "true.executable=cat" >> .hg/hgrc
  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2
  merging f
  revision 1
  space
  revision 0
  space
  revision 2
  space
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

and true.executable set to cat with path works:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=cat
  merging f
  revision 1
  space
  revision 0
  space
  revision 2
  space
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

#if unix-permissions

environment variables in true.executable are handled:

  $ echo 'echo "custom merge tool"' > .hg/merge.sh
  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg --config merge-tools.true.executable='sh' \
  >    --config merge-tools.true.args=.hg/merge.sh \
  >    merge -r 2
  merging f
  custom merge tool
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

#endif

Tool selection and merge-patterns

merge-patterns specifies new tool false:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-patterns.f=false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

merge-patterns specifies executable not found in PATH and gets warning:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=nonexistentmergetool
  couldn't find merge tool true specified for f
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

merge-patterns specifies executable with bogus path and gets warning:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=/nonexistent/mergetool
  couldn't find merge tool true specified for f
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

ui.merge overrules priority

ui.merge specifies false:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

ui.merge specifies internal:fail:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:fail
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

ui.merge specifies :local (without internal prefix):

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=:local
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

ui.merge specifies internal:other:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:other
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 2
  space
  # hg stat
  M f

ui.merge specifies internal:prompt:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:prompt
   no tool found to merge f
  keep (l)ocal or take (o)ther? l
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

ui.merge specifies internal:dump:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:dump
  merging f
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.base
  ? f.local
  ? f.orig
  ? f.other

f.base:

  $ cat f.base
  revision 0
  space

f.local:

  $ cat f.local
  revision 1
  space

f.other:

  $ cat f.other
  revision 2
  space
  $ rm f.base f.local f.other

ui.merge specifies internal:other but is overruled by pattern for false:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:other --config merge-patterns.f=false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

Premerge

ui.merge specifies internal:other but is overruled by --tool=false

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config ui.merge=internal:other --tool=false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

HGMERGE specifies internal:other but is overruled by --tool=false

  $ HGMERGE=internal:other ; export HGMERGE
  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --tool=false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

  $ unset HGMERGE # make sure HGMERGE doesn't interfere with remaining tests

update is a merge ...

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg debugsetparent 0
  $ hg update -r 2
  merging f
  revision 1
  space
  revision 0
  space
  revision 2
  space
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

update should also have --tool

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg debugsetparent 0
  $ hg update -r 2 --tool false
  merging f
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

Default is silent simplemerge:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 3
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  revision 3
  # hg stat
  M f

.premerge=True is same:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 3 --config merge-tools.true.premerge=True
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  revision 3
  # hg stat
  M f

.premerge=False executes merge-tool:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 3 --config merge-tools.true.premerge=False
  merging f
  revision 1
  space
  revision 0
  space
  revision 0
  space
  revision 3
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

premerge=keep keeps conflict markers in:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 4 --config merge-tools.true.premerge=keep
  merging f
  <<<<<<< local: ef83787e2614  - test: revision 1
  revision 1
  space
  =======
  revision 4
  >>>>>>> other: 81448d39c9a0 - test: revision 4
  revision 0
  space
  revision 4
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  <<<<<<< local: ef83787e2614  - test: revision 1
  revision 1
  space
  =======
  revision 4
  >>>>>>> other: 81448d39c9a0 - test: revision 4
  # hg stat
  M f

premerge=keep-merge3 keeps conflict markers with base content:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 4 --config merge-tools.true.premerge=keep-merge3
  merging f
  <<<<<<< local: ef83787e2614  - test: revision 1
  revision 1
  space
  ||||||| base
  revision 0
  space
  =======
  revision 4
  >>>>>>> other: 81448d39c9a0 - test: revision 4
  revision 0
  space
  revision 4
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  <<<<<<< local: ef83787e2614  - test: revision 1
  revision 1
  space
  ||||||| base
  revision 0
  space
  =======
  revision 4
  >>>>>>> other: 81448d39c9a0 - test: revision 4
  # hg stat
  M f


Tool execution

set tools.args explicit to include $base $local $other $output:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=head --config merge-tools.true.args='$base $local $other $output' \
  >   | sed 's,==> .* <==,==> ... <==,g'
  merging f
  ==> ... <==
  revision 0
  space
  
  ==> ... <==
  revision 1
  space
  
  ==> ... <==
  revision 2
  space
  
  ==> ... <==
  revision 1
  space
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f

Merge with "echo mergeresult > $local":

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > $local'
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  mergeresult
  # hg stat
  M f

- and $local is the file f:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > f'
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  mergeresult
  # hg stat
  M f

Merge with "echo mergeresult > $output" - the variable is a bit magic:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > $output'
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ aftermerge
  # cat f
  mergeresult
  # hg stat
  M f

Merge using tool with a path that must be quoted:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ cat <<EOF > 'my merge tool'
  > cat "\$1" "\$2" "\$3" > "\$4"
  > EOF
  $ hg --config merge-tools.true.executable='sh' \
  >    --config merge-tools.true.args='"./my merge tool" $base $local $other $output' \
  >    merge -r 2
  merging f
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ rm -f 'my merge tool'
  $ aftermerge
  # cat f
  revision 0
  space
  revision 1
  space
  revision 2
  space
  # hg stat
  M f

Issue3581: Merging a filename that needs to be quoted
(This test doesn't work on Windows filesystems even on Linux, so check
for Unix-like permission)

#if unix-permissions
  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ echo "revision 5" > '"; exit 1; echo "'
  $ hg commit -Am "revision 5"
  adding "; exit 1; echo "
  warning: filename contains '"', which is reserved on Windows: '"; exit 1; echo "'
  $ hg update -C 1 > /dev/null
  $ echo "revision 6" > '"; exit 1; echo "'
  $ hg commit -Am "revision 6"
  adding "; exit 1; echo "
  warning: filename contains '"', which is reserved on Windows: '"; exit 1; echo "'
  created new head
  $ hg merge --config merge-tools.true.executable="true" -r 5
  merging "; exit 1; echo "
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg update -C 1 > /dev/null
#endif

Merge post-processing

cat is a bad merge-tool and doesn't change:

  $ beforemerge
  [merge-tools]
  false.whatever=
  true.priority=1
  true.executable=cat
  # hg update -C 1
  $ hg merge -y -r 2 --config merge-tools.true.checkchanged=1
  merging f
  revision 1
  space
  revision 0
  space
  revision 2
  space
   output file f appears unchanged
  was merge successful (yn)? n
  merging f failed!
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ aftermerge
  # cat f
  revision 1
  space
  # hg stat
  M f
  ? f.orig

#if symlink

internal merge cannot handle symlinks and shouldn't try:

  $ hg update -q -C 1
  $ rm f
  $ ln -s symlink f
  $ hg commit -qm 'f is symlink'
  $ hg merge -r 2 --tool internal:merge
  merging f
  warning: internal :merge cannot merge symlinks for f
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]

#endif