[PATCH 5 of 6 foldmap-in-C] encoding.upper: factor out fallback code

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1427873441 25200
#      Wed Apr 01 00:30:41 2015 -0700
# Node ID 88ddff56632adc32943a5b8d82c666536b9395d9
# Parent  134dd4b964369e65530f72f453937a52220ef3e7
encoding.upper: factor out fallback code

This will be used as the fallback function on Windows.

diff --git a/mercurial/encoding.py b/mercurial/encoding.py
--- a/mercurial/encoding.py
+++ b/mercurial/encoding.py
@@ -338,7 +338,9 @@ def upper(s):
     try:
         return asciiupper(s)
     except UnicodeDecodeError:
-        pass
+        return upperfallback(s)
+
+def upperfallback(s):
     try:
         if isinstance(s, localstr):
             u = s._utf8.decode("utf-8")