diff -r 151cc3b3d799 -r df448de7cf3b mercurial/revlog.py
--- a/mercurial/revlog.py	Sat Aug 13 12:18:58 2016 +0900
+++ b/mercurial/revlog.py	Sat Aug 13 12:23:56 2016 +0900
@@ -32,12 +32,14 @@
     ancestor,
     error,
     mdiff,
-    parsers,
+    policy,
     pycompat,
     templatefilters,
     util,
 )
 
+parsers = policy.importmod(r'parsers')
+
 _pack = struct.pack
 _unpack = struct.unpack
 # Aliased for performance.