[FIX] stock: add procurement group for extra moves in picking

When pack operations generate extra moves, they should
take the same procurement group as those of the picking.

That way, when invoicing, they will be put on the same
invoice when there is a different invoice address on the
sale order.

addons/stock/stock.py

@@ -1362,6 +1362,7 @@ class stock_picking(osv.osv):
             'name': _('Extra Move: ') + name,
             'state': 'draft',
             'restrict_partner_id': op.owner_id,
+            'group_id': picking.group_id.id,
             }
         return res