diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -75,9 +75,14 @@ def _revancestors(repo, revs, followfirs
             if current not in seen:
                 seen.add(current)
                 yield current
-                for parent in cl.parentrevs(current)[:cut]:
-                    if parent != node.nullrev:
-                        heapq.heappush(h, -parent)
+                try:
+                    for parent in cl.parentrevs(current)[:cut]:
+                        if parent != node.nullrev:
+                            heapq.heappush(h, -parent)
+                except error.WdirUnsupported:
+                    for parent in repo[current].parents()[:cut]:
+                        if parent.rev() != node.nullrev:
+                            heapq.heappush(h, -parent.rev())
 
     return generatorset(iterate(), iterasc=False)
 
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -1231,6 +1231,16 @@ Test working-directory revision
   2147483647
   $ hg debugrevspec 'wdir()~3'
   5
+  $ hg debugrevspec 'ancestors(wdir())'
+  0
+  1
+  2
+  3
+  4
+  5
+  6
+  7
+  2147483647
   $ hg debugrevspec 'wdir()~0'
   2147483647
   $ hg debugrevspec 'p1(wdir())'