Follow up to:
ffdf507e (adding GDAL 2.0 support)
ebaa2fef (confirming GDAL 2.1 support)
8c777888 (removing GDAL 1.8, 1.7 support)

Fixed #28089 -- Removed requirement to implement get_short_name() and get_full_name() in AbstractBaseUser subclasses.

When a connection pooler is set up in transaction pooling mode, queries
relying on server-side cursors fail. The DISABLE_SERVER_SIDE_CURSORS
setting in DATABASES disables server-side cursors for this use case.

Fixed #28175 -- Fixed __in lookups on a foreign key when using the foreign key's parent model as the lookup value.

Thanks Simon Charette for review.

This facilitates other changes like refs #28160.

Thanks Tim for the review.

Regression in 38575b00.

Regression in 4a246a02.

Regression in b52c7300.

Thanks Marc Tamlyn for the report and Ian Foote/Tim Graham for review.

As CharField.to_python() now always calls str(), assigning bytes to a
CharField is no longer correct usage. Doing so results in a warning:

  django/db/models/fields/__init__.py:1061: BytesWarning: str() on a bytes instance

Use a unique constraint violation to trigger the database error instead.

Warning introduced in 301de774.

Lookup right hand side processing was compiling query compilers which happened
to work by chance as SQLCompiler defines a as_sql() method with two optional
parameters albeit it doesn't expect the same type of arguments.

Thanks Preston Timmons for review.