cleanup: remove compatibility code for Python < 2.7.1

The minimum supported Python version was recently raised to 2.7.4.

mercurial/windows.py

@@ -476,9 +476,6 b' def shellsplit(s):'
 
 def quotecommand(cmd):
     """Build a command string suitable for os.popen* calls."""
-    if sys.version_info < (2, 7, 1):
-        # Python versions since 2.7.1 do this extra quoting themselves
-        return b'"' + cmd + b'"'
     return cmd