$ hg init repo
$ cd repo
$ echo line 1 > foo
$ hg ci -qAm 'add foo'
copy foo to bar and change both files
$ hg cp foo bar
$ echo line 2-1 >> foo
$ echo line 2-2 >> bar
$ hg ci -m 'cp foo bar; change both'
in another branch, change foo in a way that doesn't conflict with
the other changes
$ hg up -qC 0
$ echo line 0 > foo
$ hg cat foo >> foo
$ hg ci -m 'change foo'
created new head
we get conflicts that shouldn't be there
$ hg merge -P
changeset: 1:484bf6903104
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: cp foo bar; change both
$ hg merge --debug
searching for copies back to rev 1
unmatched files in other:
bar
all copies found (* = to merge, ! = divergent):
bar -> foo *
checking for directory renames
resolving manifests
overwrite None partial False
ancestor e6dc8efe11cc local 6a0df1dad128+ remote 484bf6903104
foo: versions differ -> m
foo: remote copied to bar -> m
preserving foo for resolve of bar
preserving foo for resolve of foo
updating: foo 1/2 files (50.00%)
picked tool 'internal:merge' for bar (binary False symlink False)
merging foo and bar to bar
my bar@6a0df1dad128+ other bar@484bf6903104 ancestor foo@e6dc8efe11cc
premerge successful
updating: foo 2/2 files (100.00%)
picked tool 'internal:merge' for foo (binary False symlink False)
merging foo
my foo@6a0df1dad128+ other foo@484bf6903104 ancestor foo@e6dc8efe11cc
premerge successful
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
contents of foo
$ cat foo
line 0
line 1
line 2-1
contents of bar
$ cat bar
line 0
line 1
line 2-2