revancestors: replace `descending` with `sort(reverse=False)`

mercurial/revset.py

@@ -26,7 +26,7 b' def _revancestors(repo, revs, followfirs'
         revqueue, revsnode = None, None
         h = []
 
-        revs.descending()
+        revs.sort(reverse=True)
         revqueue = util.deque(revs)
         if revqueue:
             revsnode = revqueue.popleft()