diff -r 2bde971474d2 -r f3a1089654e3 mercurial/pycompat.py
--- a/mercurial/pycompat.py	Sat Oct 08 05:26:18 2016 -0400
+++ b/mercurial/pycompat.py	Sat Oct 08 08:35:43 2016 -0400
@@ -74,8 +74,10 @@
 
     def _registeraliases(self, origin, items):
         """Add items that will be populated at the first access"""
-        self._aliases.update((item.replace('_', '').lower(), (origin, item))
-                             for item in items)
+        items = map(sysstr, items)
+        self._aliases.update(
+            (item.replace(sysstr('_'), sysstr('')).lower(), (origin, item))
+            for item in items)
 
     def __getattr__(self, name):
         try: