Fixes has-many-dobule-linked join table attribute changes on injected setter

I'm not quite sure how the first version should've worked since the foreign
keys are afaik always prefixed with the table name which results in
mytable.mytable_id.

This commit keeps the old behavior as first try to remain backwards compatible.
Merge pull request #1923 from LJ1102/fix-has-many-double-linked-join-table-attribute-updates

Fixes has-many-dobule-linked join table attribute changes on injected setter