qa: new ConnectionFilter.retry()

Unused but it is likely to be useful in the future.

neo/tests/threaded/__init__.py

@@ -526,6 +526,11 @@ class ConnectionFilter(object):
                     return True
         return False
 
+    @classmethod
+    def retry(cls):
+        with cls.lock:
+            cls._retry()
+
     @classmethod
     def _retry(cls):
         for conn, queue in cls.filter_queue.items():