D7974: merge: when rename was made on both sides, use ancestor as merge base

[pulkit (Pulkit Goyal)]

pulkit added a comment.


  `test-rename-merge1.t` fails with this patch. Looks like there is one more instance of prompt which is not needed anymore. I didn't amend that in flight as I was not sure.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7974/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7974

To: martinvonz, #hg-reviewers, durin42, pulkit
Cc: durin42, marmoute, mercurial-devel