Reviewed in https://codereview.appspot.com/39670044/.
Reviewed in https://codereview.appspot.com/39670044/.

Fix join on list.

jonparrott/oauth2client,google/oauth2client,clancychilds/oauth2client,clancychilds/oauth2client,google/oauth2client,googleapis/google-api-python-client,jonparrott/oauth2client,googleapis/oauth2client,googleapis/oauth2client,googleapis/google-api-python-client