Make dict.keys() PY3 compatible

The dict.keys()[0] will raise a TypeError in PY3,
as dict.keys() doesn't return a list any more in PY3
but a view of list.

Change-Id: Ia6c0783ca8c8514a06defbeed0fa9ef24bbd9d4a
Closes-Bug: #1583419

cinderclient/openstack/common/apiclient/exceptions.py

@@ -426,7 +426,7 @@ def from_response(response, method, url):
             pass
         else:
             if hasattr(body, "keys"):
-                error = body[body.keys()[0]]
+                error = body[list(body.keys())[0]]
                 kwargs["message"] = error.get("message", None)
                 kwargs["details"] = error.get("details", None)
     elif content_type.startswith("text/"):