Respoect max_inlight message count in reconnect

Previously if the message queue filled up for some reason like bad
connection and the client disconnected (due to e.g. bad connection),
it would send all of it's messages in _out_messages-queue and not
respect _max_inflight_messages parameter. With some brokers and
when we had 1000s of messages in queue and all being sent with
qos 1 without any regard to the _max_inflight_messages, the broker
would disconnect us or the connection would again break down.

This patch makes sure _max_inflight_messages is respected when
reconnect happens for any reason.

I believe this also fixes eclipse#492

Signed-off-by: Juha Ylikoski <juha.ylikoski@treon.fi>

src/paho/mqtt/client.py

@@ -2945,16 +2945,18 @@ def _check_clean_session(self):
     def _messages_reconnect_reset_out(self):
         with self._out_message_mutex:
             self._inflight_messages = 0
+            to_be_inflight = 0
             for m in self._out_messages.values():
                 m.timestamp = 0
-                if self._max_inflight_messages == 0 or self._inflight_messages < self._max_inflight_messages:
+                if self._max_inflight_messages == 0 or to_be_inflight < self._max_inflight_messages:
                     if m.qos == 0:
                         m.state = mqtt_ms_publish
                     elif m.qos == 1:
                         # self._inflight_messages = self._inflight_messages + 1
                         if m.state == mqtt_ms_wait_for_puback:
                             m.dup = True
                         m.state = mqtt_ms_publish
+                        to_be_inflight += 1
                     elif m.qos == 2:
                         # self._inflight_messages = self._inflight_messages + 1
                         if self._check_clean_session():
@@ -2968,6 +2970,7 @@ def _messages_reconnect_reset_out(self):
                                 if m.state == mqtt_ms_wait_for_pubrec:
                                     m.dup = True
                                 m.state = mqtt_ms_publish
+                        to_be_inflight += 1
                 else:
                     m.state = mqtt_ms_queued