$ hg init t

  $ cd t

  $ echo 1 > a

  $ hg ci -qAm "first"

  $ hg cp a b

  $ hg mv a c

  $ echo 2 >> b

  $ echo 2 >> c

  $ hg ci -qAm "second"

  $ hg co -C 0

  1 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ echo 0 > a

  $ echo 1 >> a

  $ hg ci -qAm "other"

  $ hg merge --debug

    searching for copies back to rev 1

    unmatched files in other:

     b

     c

    all copies found (* = to merge, ! = divergent, % = renamed and deleted):

     src: 'a' -> dst: 'b' *

     src: 'a' -> dst: 'c' *

    checking for directory renames

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: b8bf91eeebbc, local: add3f11052fa+, remote: 17c05bb7fcb6

   b: remote moved from a -> m

    preserving a for resolve of b

   c: remote moved from a -> m

    preserving a for resolve of c

  removing a

  updating: b 1/2 files (50.00%)

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

  merging a and b to b

  my b@add3f11052fa+ other b@17c05bb7fcb6 ancestor a@b8bf91eeebbc

   premerge successful

  updating: c 2/2 files (100.00%)

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

  merging a and c to c

  my c@add3f11052fa+ other c@17c05bb7fcb6 ancestor a@b8bf91eeebbc

   premerge successful

  0 files updated, 2 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

file b

  $ cat b

  0

  1

  2

file c

  $ cat c

  0

  1

  2

  $ cd ..