avoid the reserved bits

Author: vladak

adafruit_minimqtt/adafruit_minimqtt.py

@@ -903,7 +903,7 @@ def _wait_for_msg(self, timeout=0.1):
         if res in [None, b"", b"\x00"]:
             # If we get here, it means that there is nothing to be received
             return None
-        if res[0] == MQTT_PINGRESP:
+        if res[0] & 0xF0 == MQTT_PINGRESP:
             if self.logger is not None:
                 self.logger.debug("Got PINGRESP")
             sz = self._sock_exact_recv(1)[0]