* Remove the 'set default from all bitflags items' behavior of
`RNA_def_property_enum_bitflag_sdna`.
* Add some minimal sanity check regarding bitflag enums that also define
an `items` runtime callback.
It currently assumes that if a valid set of items is also statically
defined, the items callback will return a subset of these.
Implements #143538.
Pull Request: https://projects.blender.org/blender/blender/pulls/143733
d415890708