hgext/mq.py

--- a/hgext/mq.py	Fri Mar 02 07:15:54 2018 +0530
+++ b/hgext/mq.py	Fri Mar 02 07:16:33 2018 +0530
@@ -780,7 +780,7 @@
 
         diffopts = self.patchopts(diffopts, patch)
         patchf = self.opener(patch, "w")
-        comments = str(ph)
+        comments = bytes(ph)
         if comments:
             patchf.write(comments)
         self.printdiff(repo, diffopts, head, n, fp=patchf)