Made opener return an OSFS rather thatn an SubFS, where appropriate

fs/opener.py

@@ -67,6 +67,7 @@ __all__ = ['OpenerError',
            'HTTPOpener']
 
 from fs.path import pathsplit, join, iswildcard, normpath
+from fs.osfs import OSFS
 from fs.filelike import FileWrapper
 from os import getcwd
 import os.path
@@ -290,8 +291,11 @@ class OpenerRegistry(object):
         
         """        
         fs, path = self.parse(fs_url, writeable=writeable, create_dir=create_dir)        
+        if path and '://' not in fs_url:
+            # A shortcut to return an OSFS rather than a SubFS for os paths
+            return OSFS(fs_url)
         if path:
-            return fs.opendir(path)
+            fs = fs.opendir(path)
         return fs