Summary:
This solves an issue vipannalla saw that the heuristics logic behaves incorrectly
when running `hg up -C c4a88583; hg graft 23001ead`. The file `great_persons_on_ex_civilization-inl.h`
would be marked as "unresolved" and removed from the working copy potentially
due to other mergedriver actions, while it should be merged cleanly and do not
appear in mergestate at all.
After debugging, the file was only renamed on one side, and not changed on the
other side. In the heuristics code path, the file was reported as copied and
confused the callsite.
Reviewed By: singhsrb
Differential Revision: D14195031
fbshipit-source-id: 0602fd56b75219f851c0175debfe72c4d49d652d
