import OrderedDict from git.odict rather than directly from collections, to pix Py2.6 compatibility

Author: boegel

Diff for: git/cmd.py

@@ -13,7 +13,7 @@
 import errno
 import mmap
 
-from collections import OrderedDict
+from git.odict import OrderedDict
 
 from contextlib import contextmanager
 import signal