umqtt.robust: When reconnecting, close the previous socket.

Author: jef

micropython/umqtt.robust/umqtt/robust.py

@@ -20,6 +20,11 @@ def log(self, in_reconnect, e):
     def reconnect(self):
         i = 0
         while 1:
+            try:
+                if self.sock:
+                    self.sock.close()
+            except OSError as e:
+                self.log(True, e)
             try:
                 return super().connect(False)
             except OSError as e: