Polymorphic `where`s should be treated as a unit.

[pvande]

ActiveRecord's default behavior around .where.not(hash) is to ensure that each key is appropriately filtered out from the query, with the effect being that the query is populated with (key1 != value1) AND (key2 != value2). In general, this feels like a fair implementation, despite not being a direct negation of .where(hash).

However, ActiveRecord also supports filtering on a polymorphic association. This works as expected, internally being expanded to a condition that verifies both the relation_id and the relation_type. Negating one of these conditions, however, excludes rows that share a relation_type or a relation_id.

Fixes #16983.

[pvande]

The build error was a single job timing out for seemingly unrelated reasons.

[matthewd]

xref #14161

[pywebdesign]

+1

[MisinformedDNA]

There's a series of issues leading back to this one. But in order for any of them to close, this once needs to be merged. Any reason this hasn't been merged yet?

[teknull]

@MisinformedDNA Looks like the CI build failed with merge conflicts. Someone from core will need to sort those out before it can pass.