GerritWatcher: add poll_timeout

So that zuul reload process can happen when gerrit stream is silent.
Otherwise the main loop doesn't exit out of the poll call and doesn't
evaluate the "while not self._stopped" location.

Change-Id: If3129a65da6119acf69ad00e2e78c7ec82a49941
Closes-Bug: https://storyboard.openstack.org/#!/story/2000472
1 file changed