--- a/mercurial/mdiff.py	Sat Mar 03 07:00:37 2018 -0500
+++ b/mercurial/mdiff.py	Sat Mar 03 07:24:25 2018 -0500
@@ -30,9 +30,17 @@
 fixws = bdiff.fixws
 patches = mpatch.patches
 patchedsize = mpatch.patchedsize
-textdiff = bdiff.bdiff
+_textdiff = bdiff.bdiff
 splitnewlines = bdiff.splitnewlines
 
+# On Python 3, util.buffer() creates a memoryview, which appears not
+# supporting the buffer protocol
+if pycompat.ispy3:
+    def textdiff(a, b):
+        return _textdiff(bytes(a), bytes(b))
+else:
+    textdiff = _textdiff
+
 class diffopts(object):
     '''context is the number of context lines
     text treats all files as text