--- a/mercurial/util.py	Thu Jul 13 23:43:16 2017 -0700
+++ b/mercurial/util.py	Tue May 16 11:00:38 2017 -0700
@@ -3209,6 +3209,7 @@
     while pos != -1:
         yield path[:pos]
         pos = path.rfind('/', 0, pos)
+    yield ''
 
 
 # convenient shortcut