Added release note for #21410; thanks Loic.
Release notes for ORM changes in 1.6
Propagate get_user_model exception from get_user

Fixes #21439
Merge pull request #1920 from mattrobenolt/unboundlocalerror

Fixed #21439 -- Propagated get_user_model exception from get_user
Fixed #21432 -- DateTimeQuery now copies tzinfo when cloning.

Thanks Enrique Martínez for the report and @bmispelon for the tests.
Added backported fixes to 1.6.1 release notes.
Fixed typo and slightly improved error message when db is missing time zone definitions.

Refs #21432.