Thanks Tim Graham for the review.

Regression in 2f9861d8.

These functions do nothing on Python 3.

Thanks Tim Graham for the review.

Thanks Tim Graham and Simon Charette for the reviews.

Thanks Tim Graham for the review.

Thanks Tim Graham for the initial patch.

When a FileField is set to an instance of File that is not also an
instance of FieldFile, pre_save() passes that object as the contents to
Storage.save(). This allows the file to be moved rather than copied
to the upload destination.

Follow up to 67d98441.

This behavior was removed in 67d98441
but is needed to prevent a crash in formtools.

Thanks Tim Graham for completing the initial patch.

The only reason why GenericForeignKey and GenericRelation are stored
separately inside _meta is that they need to be cloned for every model
subclass, but that's not true for any other virtual field. Actually,
it's only true for GenericRelation.

This partially reverts commit bc7d201b.

Thanks Tim for the review.

Refs #25858.

Thanks to Karl Hobley for the report and Markus, Shai, Aymeric for their input
and Tim for the review.