Fixed #28710 -- Fixed the Basque DATE_FORMAT string

[claudep]

Thanks Eneko Illarramendi for the report and initial patch.

[timgraham]

Please add with self.subTest(locale=locale): after the for loop (except on stable/1.11.x where Python 2 support is needed).

[claudep]

Don't you mind combining the with conditions?
with self.subTest(locale=locale), translation.override(locale):

[timgraham]

I tried that locally but it didn't seem to work.

[claudep]

Weird, it works fine on my system (Python 3.5). What error do you get?

[timgraham]

I guess I had made a mistake earlier, seems to work now.