py3: use pycompat.bytestr to convert _b85chars to bytes

The tranformer does append b'' to the value and make that a bytes but bytes in
Python 3 returns the ascii value on getting characters using indexing.
Characters of this string are queried using indexing multiple times in the file
and to support that we use pycompat.bytestr which returns the bytechrs using
indexing.

Differential Revision: https://phab.mercurial-scm.org/D2072

mercurial/pure/base85.py

@@ -9,8 +9,10 b' from __future__ import absolute_import'
 
 import struct
 
-_b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
-            "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
+from .. import pycompat
+
+_b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef"
+                             "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")
 _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
 _b85dec = {}