diff -r 649d3ac37a12 -r d783f945a701 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Sun Oct 06 19:25:18 2019 -0400
+++ b/mercurial/filemerge.py	Mon Oct 07 00:04:04 2019 -0400
@@ -1231,7 +1231,7 @@
 def loadinternalmerge(ui, extname, registrarobj):
     """Load internal merge tool from specified registrarobj
     """
-    for name, func in registrarobj._table.iteritems():
+    for name, func in pycompat.iteritems(registrarobj._table):
         fullname = b':' + name
         internals[fullname] = func
         internals[b'internal:' + name] = func