D4324: setdiscovery: use revset for resolving DAG heads in a subset

[yuja (Yuya Nishihara)]

yuja added a comment.


  >   For reasons I didn't investigate, feeding a set with nullrev
  >   into the heads() revset resulted in a bunch of tests failing.
  >   Filtering out nullrev from the input set fixes things.
  
  That's probably because `heads()` internally calls `parents()`, but
  `parents()` doesn't handle null in a way `heads()` can exclude p1 of the
  root revision.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D4324

To: indygreg, #hg-reviewers
Cc: yuja, mercurial-devel