My DM-25354 merge have broken unit test for Postgres (and I think for Oracle too):

        # cannot store empty key or value

        with self.assertRaises(Exception):

>           attributes.set("", "value")

E           AssertionError: Exception not raised

The issue is with the handling handling of the empty strings, our sqlite backend adds constraint to the schema which disables empty strings, that was done to work around Oracle issue that treats empty strings as NULLS. as a result the code now raises integrity exception when saving empty string to database in sqlite case but there is no similar check for oracle/sqlite so that works OK.

Simplest fix for my case would be either to suppress this check in the test completely or to add a new check in attribute manager that raises exception independently of a backend.