dagutil: use revlog.parentrevs() for resolving parent revisions And remove parents() since it is no longer used. revlog.parentrevs() is almost the same as parents(). The main difference is that parentrevs() can return nullrev. dagop.headrevs() already handles nullrev. We add an inline check for nullrev in the other call site to account for the difference. .. api:: parents() removed from dagutil classes Use parentrevs() on the storage object instead. Differential Revision: https://phab.mercurial-scm.org/D4328