Update session.py

[iLaus]

            # for huawei fireworks, you need change NetconfBase.BASE_11, when you received device return.
            # in gevent , the function _post_connect's init_event.wait(timeout) can not work.
            # you can add gevent.sleep(0.1) before(or replace) init_event.wait(timeout) .
            # or change the order of the send and receive.
            # when you send first, the self._base woun't change NetconfBase.BASE_11.

[iLaus]

How about my suggestion? @einarnn

[coveralls]

coverage: 82.824% (+0.4%) from 82.468%
when pulling 6641f73 on iLaus:master
into f0f4d95 on ncclient:master.