Currently, the logging docs are a bit ambiguous or at least not completely clear as to when events are propagated when Logger.propagate is true. The docs currently say [1]--

"If [the `propagate`] attribute evaluates to true, events logged to this logger will be passed to the handlers of higher level (ancestor) loggers, in addition to any handlers attached to this logger."

But it's not clear if "logged to this logger" means (1) a log method like info() or error() was called on the logger, or (2) the event was passed to the logger's handlers (i.e. satisfied the logger's log level threshold and any filters).

Empirically, I found that the meaning is (2).

[1]: https://docs.python.org/3/library/logging.html#logging.Logger.propagate