asyncio: BaseEventLoop._assert_is_current_event_loop() now only raises an

exception if the current loop is not None.

Guido van Rossum wrote:

"The behavior that you can set the loop to None (and keep track of it
explicitly) is part of the spec, and this should still be supported even in
debug mode. The behavior that we raise an error if you are caught having
multiple active loops per thread is just a debugging heuristic, and it
shouldn't break code that follows the spec."

Lib/asyncio/base_events.py

@@ -327,7 +327,8 @@ class BaseEventLoop(events.AbstractEventLoop):
         Should only be called when (self._debug == True). The caller is
         responsible for checking this condition for performance reasons.
         """
-        if events.get_event_loop() is not self:
+        current = events.get_event_loop()
+        if current is not None and current is not self:
             raise RuntimeError(
                 "non-threadsafe operation invoked on an event loop other "
                 "than the current one")