make_bytes() assumed that if the Content-Encoding header is set, then
everything had already been dealt with bytes-wise, but in a streaming
situation this was not necessarily the case.

make_bytes() is only called when necessary when working with a
StreamingHttpResponse iterable, but by that point the middleware has
added the Content-Encoding header and thus make_bytes() tried to call
bytes(value) (and dies). If it had been a normal HttpResponse,
make_bytes() would have been called when the content was set, well
before the middleware set the Content-Encoding header.

This commit removes the special casing when Content-Encoding is set,
allowing unicode strings to be encoded during the iteration before they
are e.g. gzipped. This behaviour was added a long time ago for #4969 and
it doesn't appear to be necessary any more, as everything is correctly
made into bytes at the appropriate places.

Two new tests, to show that supplying non-ASCII characters to a
StreamingHttpResponse works fine normally, and when passed through the
GZip middleware (the latter dies without the change to make_bytes()).
Removes the test with a nonsense Content-Encoding and Unicode input - if
this were to happen, it can still be encoded as bytes fine.

The method is mainly intended for use with UUIDField. For UUIDField we
want to call the field's default even when primary key value is
explicitly set to None to match the behavior of AutoField.

Thanks to Marc Tamlyn and Tim Graham for review.

Thanks jekka-ua for the report and patch.

Specifically in rendering shortcuts, template responses, and class-based
views that return template responses.

Also added a test for render_to_response(status=...) which was missing
from fdbfc980.

Thanks Tim and Carl for the review.

This function is unused since dce820ff
after being introduced in 718a5ba1

Fixed #24255 -- Specifed 'fields' parameter in modelformset_factory / inlineformset_factory examples.

This function is unused since 6fe2b001

This method is unused since f567d04b

This method was inadvertently reintroduced in
f59fd15c

This method is unused since 337d102b

Needed for tests for migrations handling of database defaults.

This method is unused since 8717b066.

This reverts commit da79ccca.

This optimized the unsuccessful case at the expense of the successful one.

Thanks Anssi Kääriäinen, Marc Tamlyn, and Tim Graham for the reviews.

An explicit `__exact` lookup in the related managers filters
was interpreted as a reference to a foreign `exact` field.

Thanks to Trac alias zhiyajun11 for the report, Josh for the investigation,
Loïc for the test name and Tim for the review.

Reference: http://lh.2xlibre.net/locale/fa_IR/

Django imports threading in many other places without fallback.

Removed unused method and updated docstrings.

Thanks Tom Christie for the report and review.