Cleaned up a repr() hack that caused problems on Python3.
Fixed typo in internal CharField method
Fixed spelling in model_forms test class names
Fixed #22085 -- Added a feature for setting non-expiring keys as the default.

This feature allows the default `TIMEOUT` Cache argument to be set to `None`,
so that cache instances can set a non-expiring key as the default,
instead of using the default value of 5 minutes.

Previously, this was possible only by passing `None` as an argument to
the set() method of objects of type `BaseCache` (and subtypes).
Added tests for MTI in RunPython.
Fixed #21893 -- ModelState didn't account for MTI parents inherited from abstract models.
Merge pull request #2396 from loic/ticket21893

Fixed #21893 -- ModelState didn't account for MTI parents inherited from abstract models.
Fixed incorrect docstring in cache tests
Fixed three small flake8 violations.
Fixed #7571 -- Fixed parameter matching in include()'d urlpattern

Fixed URL resolving in the case where an outer regex includes an inner
regex and both regexes use positional parameters instead of named
groups, causing the outer regex's parameters to override the inner
regex's.

Modified the regex url resolver so that it will concatenates and then
normalizes, instead of normalizing and then concatenating.