[PATCH 2 of 8] py3: add os.fsdecode() as pycompat.fsdecode()

[Pulkit Goyal]

# HG changeset patch
# User Pulkit Goyal <7895pulkit at gmail.com>
# Date 1478382160 -19800
#      Sun Nov 06 03:12:40 2016 +0530
# Node ID 972b0c0175fc402ffe8beac276b737b32ce0df0b
# Parent  2d456de3a41ab961da8ae71dfefccdc9d7febe78
py3: add os.fsdecode() as pycompat.fsdecode()

We need to use os.fsdecode() but this was not present in Python 2. So added
the function in pycompat.py

diff -r 2d456de3a41a -r 972b0c0175fc mercurial/pycompat.py
--- a/mercurial/pycompat.py	Sun Nov 06 02:59:43 2016 +0530
+++ b/mercurial/pycompat.py	Sun Nov 06 03:12:40 2016 +0530
@@ -36,6 +36,7 @@
     import functools
     import os
     fsencode = os.fsencode
+    fsdecode = os.fsdecode
 
     def sysstr(s):
         """Return a keyword str to be passed to Python functions such as
@@ -76,6 +77,11 @@
             raise TypeError(
                 "expect str, not %s" % type(filename).__name__)
 
+    # In Python 2, fsdecode() have a very chances to recieve bytes. So it's
+    # better not to touch Python 2 part as its already working fine.
+    def fsdecode(filename):
+        return filename
+
 stringio = io.StringIO
 empty = _queue.Empty
 queue = _queue.Queue