[1.7.x] Fixed #23350 -- Updated mod_wsgi auth example to use less memory.

Thanks Graham Dumpleton for the report.

Backport of c7f7432be5 from master
[1.7.x] Fixed missing trailing parenthesis in docs/releases/1.7.txt

Backport of e5ae03fd5a from master
[1.7.x] Fixed #11775 -- Made ABSOLUTE_URL_OVERRIDES work with models that don't define get_absolute_url().

Thanks jukvalim for the report and initial patch,
and Preston Timmons for review.

Backport of c32bc1a7a7 from master
[1.7.x] Fixed #22920 -- Avoid masking some exceptions.

If loading an application trigger an ImportError, the details of that
error were lost in some cases. Thanks Ben Davis for the report.

Backport of b161c01 from master
[1.7.x] Note re migrations importing custom fields

Backport of b4d486c80f from master