Use C locale when parsing git output

Setting LANG=C so that on non-English systems, the
output of git is consistent.

Author: jdmansour

nbgitpuller/pull.py

@@ -16,6 +16,7 @@ def execute_cmd(cmd, **kwargs):
     yield '$ {}\n'.format(' '.join(cmd))
     kwargs['stdout'] = subprocess.PIPE
     kwargs['stderr'] = subprocess.STDOUT
+    kwargs['env'] = dict(os.environ, LANG='C')
 
     proc = subprocess.Popen(cmd, **kwargs)