asyncio: Fix BaseEventLoop._assert_is_current_event_loop(): get_event_loop()

raises an exception if there is no current loop

Lib/asyncio/base_events.py

@@ -332,8 +332,11 @@ class BaseEventLoop(events.AbstractEventLoop):
         Should only be called when (self._debug == True). The caller is
         responsible for checking this condition for performance reasons.
         """
-        current = events.get_event_loop()
-        if current is not None and current is not self:
+        try:
+            current = events.get_event_loop()
+        except AssertionError:
+            return
+        if current is not self:
             raise RuntimeError(
                 "non-threadsafe operation invoked on an event loop other "
                 "than the current one")