diff -r a5e1393f61a2 -r 2f812b0d1936 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Mon Jun 26 17:23:10 2017 +0530
+++ b/mercurial/debugcommands.py	Mon Jun 26 23:57:49 2017 +0530
@@ -1818,7 +1818,7 @@
         # Obtain data on the raw chunks in the revlog.
         segment = r._getsegmentforrevs(rev, rev)[1]
         if segment:
-            chunktype = segment[0]
+            chunktype = bytes(segment[0:1])
         else:
             chunktype = 'empty'