What is important here, I think, is that any time arithmetic is not affected by this normalization, so if you add an hour the difference will be an hour, so you don't really have to think about it.
So somebody clearly made a mistake (either the user or the programmer not checking the input) which you can't automagically fix. Well, at least, it's a terrible idea.
I understand the intent of helping them, but you make more harm this way.
It's also against the ZEN of Python.
Obviously automatic normalisation is the correct thing to do when doing arithmetic that crosses DST-rollover boundaries (this is what the Python stdlib gets wrong), but I don't think it should be done (by default) upon creation with a location-based TZ specification:
pendulum.create(2016, 10, 30, 2, 30, 00, 0, 'Europe/Paris') is ambiguous, and pendulum.create(2016, 3, 27, 2, 30, 00, 0, 'Europe/Paris') is non-existent. pytz raises AmbiguousTimeError or NonExistentTimeError respectively in cases where you try to construct local times like that and specifiy is_dst=None: http://pytz.sourceforge.net/#problems-with-localtime
With pendulum I don't see a possibility to enforce a "strict mode" that turns of those automatic assumptions.
I think the best thing to do here is keep the current behavior (post-DST) but with an option to choose what you want exactly (post-DST, pre-DST)
> Unfortunately, during DST transitions, some datetimes don’t exist or are ambiguous. In such situations, pytz raises an exception. Other tzinfo implementations, such as the local time zone used as a fallback when pytz isn’t installed, may raise an exception or return inaccurate results. That’s why you should always create aware datetime objects when time zone support is enabled.
https://docs.djangoproject.com/en/1.10/topics/i18n/timezones...