odoo/odoo — pull request #997 by mart-e (2014-07-08 11:56:20+00:00)
Title: [FIX] ir.model.fields: better unlink

When droping a column, remove also the relation table in case of custom m2m field.
The relation table needs to be dropped otherwise an unremovable constraint to the targetted table is kept (and anyway is not needed anymore).