$ hg init repo

  $ cd repo

  $ echo line 1 > foo

  $ hg ci -qAm 'add foo' -d "1000000 0"

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' -d "1000000 0"

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' -d "1000000 0"

  created new head

we get conflicts that shouldn't be there

  $ hg merge -P

  changeset:   1:d9da848d0adf

  user:        test

  date:        Mon Jan 12 13:46:40 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 310fd17130da local 2092631ce82b+ remote d9da848d0adf

   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@2092631ce82b+ other bar@d9da848d0adf ancestor foo@310fd17130da

   premerge successful

  updating: foo 2/2 files (100.00%)

  picked tool 'internal:merge' for foo (binary False symlink False)

  merging foo

  my foo@2092631ce82b+ other foo@d9da848d0adf ancestor foo@310fd17130da

   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