Fix None comparison.

src/paho/mqtt/client.py

@@ -345,10 +345,10 @@ def wait_for_publish(self, timeout=None):
  elif self.rc > 0:
  raise RuntimeError('Message publish failed: %s' % (error_string(self.rc)))
 
- timeout_time = None if not timeout else time.time() + timeout
- timeout_tenth = None if not timeout else timeout / 10.
+ timeout_time = None if timeout is None else time.time() + timeout
+ timeout_tenth = None if timeout is None else timeout / 10.
  def timed_out():
- return False if not timeout else time.time() > timeout_time
+ return False if timeout is None else time.time() > timeout_time
 
  with self._condition:
  while not self._published and not timed_out():