fix call close_callback

Author: snower

tormysql/connections.py

@@ -40,17 +40,22 @@ def set_close_callback(self, callback):
         self._close_callback = callback
 
     def stream_close_callback(self):
+        if self._close_callback and callable(self._close_callback):
+            cb = self._close_callback
+            self._close_callback = None
+            cb()
+                
         if self.socket:
-            if self._close_callback and callable(self._close_callback):
-                self._close_callback()
             sock = self.socket
             self.socket = None
             self._rfile = None
             sock.set_close_callback(None)
 
     def close(self):
         if self._close_callback and callable(self._close_callback):
-            self._close_callback()
+            cb = self._close_callback
+            self._close_callback = None
+            cb()
 
         if self.socket is None:
             raise err.Error("Already closed")