Normalized check that ALLOWED_INCLUDE_ROOTS is a tuple.
Adjusted tests for previous commit.

The test was testing a use case that doesn't happen in real world
projects: developers don't assign settings at run time (and Django
explicitly doesn't support it).
Fix link target markup

This markup for a code block is redundant with the code-block directive below,
and blocks the following line from working as link target.
Fix malformed note directives.
Fixed #23799 -- Made makemigrations respect --no-optimize.

Thanks to yamila-moreno for the idea of a skip message.
Fixed #18714 -- Added 'fuzzy' compilemessages option
Deprecated calling a SQLCompiler instance.
Fixed #23849 -- Documented the locmem.Loader class.
Removed nonexistent module django.test._doctest from coveragerc.
Fixed #22248 -- Made RenameModel reversible
Removed a deprecated use of SQLCompiler as quote_name in GIS.
Fixed GeoSQLCompiler to pass itself correctly to column as_sql.
Formatted model states in autodetector tests
Cleaned up and reformatted autodetector tests
Simplified caching of password hashers.

load_hashers cached its result regardless of its password_hashers
argument which required fragile cache invalidation. Remove that
argument in favor of @override_settings and triggering cache
invalidation with a signal.
Simplified caching of get_default_timezone().
Simplified caching of templatetags modules.
Simplified caching of template context processors.
Removed usage of a global variable.
Simplified caching of the default exception reporter filter.

Also simplified the logic under the assumption that a false-ish object
won't have an exception_reporter_filter attribute.