diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -193,8 +193,8 @@ def rebase(ui, repo, **opts):
             if not rebaseset:
                 repo.ui.debug('base is ancestor of destination\n')
                 result = None
-            elif not keepf and list(repo.revs('first(children(%ld) - %ld)',
-                                              rebaseset, rebaseset)):
+            elif not keepf and repo.revs('first(children(%ld) - %ld)',
+                                         rebaseset, rebaseset):
                 raise util.Abort(
                     _("can't remove original changesets with"
                       " unrebased descendants"),