634
634
raise errors.NoCommits(b)
635
635
revision_source = revision.MultipleRevisionSources(
636
636
branch.repository, other_branch.repository)
638
638
revision_a = revision.ensure_null(revision_a)
639
639
revision_b = revision.ensure_null(revision_b)
640
640
if revision.NULL_REVISION in (revision_a, revision_b):
641
641
rev_id = revision.NULL_REVISION
644
644
if rev_id == revision.NULL_REVISION:
645
645
raise errors.NoCommonAncestor(revision_a, revision_b)