fix run_sync no block problem

[huangwei1024]

@coroutine
def _coroutine():
    ret = yield rpc.call_async(method, *args)
    raise Return(ret)
return self.ioloop.run_sync(_coroutine)

the example will raise TimeoutError('Operation timed out after %s seconds' % timeout)
I modified run_sync, it will be run until future was done really or timeout.

[bdarnell]

Can you provide a complete executable example that demonstrates the problem this solves? You shouldn't have to call start() more than once unless you're calling stop() somewhere that you shouldn't be. It sounds like you might be calling run_sync() while the IOLoop is already running, which won't work.

[bdarnell]

Closing because I can't reproduce any problem here; please reopen if you have more details.