diff -r 3d14e9eef3c1 -r 1c6f4970f3e8 hgext3rd/topic/revset.py
--- a/hgext3rd/topic/revset.py	Mon Mar 21 21:28:12 2016 -0700
+++ b/hgext3rd/topic/revset.py	Mon Mar 21 21:28:29 2016 -0700
@@ -1,5 +1,7 @@
+from mercurial import error
 from mercurial import revset
 from mercurial import util
+from mercurial.i18n import _
 
 from . import constants, destination, stack