[PATCH 3 of 4 py3] config: open config files as binary explicitly all the time

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1476019794 14400
#      Sun Oct 09 09:29:54 2016 -0400
# Node ID 5f29fffcc722d8993fda4155884c1aae4469d2f3
# Parent  576e4c82886c7e5cf59f7b95b38e0f3c29932581
config: open config files as binary explicitly all the time

We had been getting lucky that on posix-like systems the default for
files in Python 2 is binary IO, but now we're explicitly using binary
IO all the time.

diff --git a/mercurial/config.py b/mercurial/config.py
--- a/mercurial/config.py
+++ b/mercurial/config.py
@@ -169,5 +169,5 @@ class config(object):
 
     def read(self, path, fp=None, sections=None, remap=None):
         if not fp:
-            fp = util.posixfile(path)
+            fp = util.posixfile(path, r'rb')
         self.parse(path, fp.read(), sections, remap, self.read)