diff -r d77c3b023393 -r f659a407e5ee mercurial/revlog.py
--- a/mercurial/revlog.py	Sat Mar 03 23:49:39 2018 -0500
+++ b/mercurial/revlog.py	Sun Mar 04 22:37:41 2018 +0530
@@ -1996,7 +1996,8 @@
             try:
                 return _zlibdecompress(data)
             except zlib.error as e:
-                raise RevlogError(_('revlog decompress error: %s') % str(e))
+                raise RevlogError(_('revlog decompress error: %s') %
+                                  util.forcebytestr(e))
         # '\0' is more common than 'u' so it goes first.
         elif t == '\0':
             return data