--- a/hgext/simple4server.py	Fri Oct 28 17:15:57 2016 -0700
+++ b/hgext/simple4server.py	Fri Oct 28 17:25:06 2016 -0700
@@ -15,6 +15,7 @@
 
 import hashlib
 import struct
+from mercurial import error
 from mercurial import util
 from mercurial import wireproto
 from mercurial import extensions