fix(travis): get py2.6 to work

Seems like OSX is somewhat special here ... .

Author: Byron

git/test/test_git.py

@@ -201,7 +201,7 @@ def test_environment(self, rw_dir):
                 try:
                     remote.fetch()
                 except GitCommandError as err:
-                    if sys.version_info[0] < 3:
+                    if sys.version_info[0] < 3 and sys.platform == 'darwin':
                         assert 'ssh-origin' in str(err)
                         assert err.status == 128
                     else: