Fixed #27513 -- Made Signal.send/send_robust a tiny bit faster

[adamchainz]

Ticket

[MarkusH]

LGTM

[adamchainz]

Hang about, just realized send with receivers can be optimized with a list comp.

[adamchainz]

Test failures are all in settings_tests.tests.TestComplexSettingOverride.test_complex_override_warning which seems unrelated

[charettes]

I'm not sure yet about what's causing the failure but I can reproduce locally on Python 3.5 with your patch and cannot without it.

[adamchainz]

Oh yes, maybe something about override_settings's signal is broken 😢

[charettes]

@adamchainz it's alright you just have to change the stacklevel to 6 here which is relying on the internal of the signaling infrastructure.

[charettes]

Actually you'll have to make it 6 only on Python3. Use 5 if django.utils.six.PY2 else 6.

[charettes]

I think this is related to the scoping rule changes of list comprehension in Python 3.

[adamchainz]

Yes makes sense. Thanks!