--- a/hgext/evolve.py	Fri Jul 04 09:29:13 2014 -0400
+++ b/hgext/evolve.py	Mon Jun 30 10:27:15 2014 -0400
@@ -2098,8 +2098,7 @@
     else:
         revs = ()
     if not revs:
-        ui.write_err('no revision to fold\n')
-        return 1
+        raise util.Abort(_('no revisions specified'))
     roots = repo.revs('roots(%ld)', revs)
     if len(roots) > 1:
         raise util.Abort("set has multiple roots")