Selection of attachments through inheriting model can be useful if
we want to purge attachments that are extended through another
model.
For example, shipping.label (from base_delivery_carrier_label)
inherits from ir.attachment but the attachment itself is linked to
the stock.picking model.
By using inheriting_model defined to shipping.label and setting
model_ids to stock.picking, we can safely select the attachments
linked to stock.pickings that are shipping labels and avoid deleting
any picking list or delivery note reports.
Ignacio Buioli
Akim Juillerat
Dept. Técnico
hkpatel
Enric Tobella
Florent de Labarre