[16.0] purchase_sale_stock_inter_company : partial dropshipping deliveries is wrong

[metaminux]

Module

purchase_sale_stock_inter_company

Describe the bug

When using inter company and dropshipping, if delivery is not complete (but with partial deliveries and backorders), quantities computed as delivered in the "customer" company are wrong.

To Reproduce

16.0:

Steps to reproduce the behavior:

1. In a runboat, install purchase_sale_stock_inter_company
2. Configure My Company (Chicago) :
3. Sale from purchase = True
4. Warehouse = Chicago 1
5. Sale user = Marc Demo
6. Sale Orders Auto Validation = True
7. Configure My Company (San Francisco) :
8. Sale from purchase = True
9. Warehouse = Your Company
10. Sale user = Marc Demo
11. Sale Orders Auto Validation = True
12. Enable dropshipping
13. Configure product "FURN_6666" :
14. Dropship route = True
15. Add a first supplier price with supplier = "My Company (San Francisco)"
16. Switch to My company (Chicago)
17. Open customer "Deco Addict" and click on Sales/Quotations
18. Click New button to create a new quotation
19. Add a line for product "FURN_6666" with qty = 5
20. Confirm quotation.
21. Go to generated PO with My Company (San Francisco) as supplier and confirm it
22. Switch to My company (San Francisco)
23. Go to the new created inter company SO for customer My company (Chicago)
24. Go to the generated PO for the external suppllier (by default "Wood corner") and confirm it
25. Go to the dropship and set done quantity = 3, validate and create a backorder (everything is fine in both companies)
26. Finish the delivery (qty = 2)

Expected behavior
In both companies, we should have 2 dropship pickings for each sales orders in "done" state and quantities should be 3 for the first one and 2 for the second (the backorder).
Each sale order should have a computed delivered quanity of 5.

Here, quantities are OK in My Company (San Francisco) (the "supplier" company)
But quantities are not OK in My Company (Chicago) (the "customer" company) because quantities are reset to 0 on the first dropship picking when validating the backorder. So final computed delivered quantity is only 2 !

Additional context
The steps to reproduce are quite long, but I think the bug is related to the _action_done method of stock.picking

multi-company/purchase_sale_stock_inter_company/models/stock_picking.py

Lines 14 to 57 in c5bb14c

	def _action_done(self):
	# Only DropShip pickings
	po_picks = self.browse()
	for pick in self.filtered(
	lambda x: x.location_dest_id.usage == "customer"
	).sudo():
	purchase = pick.sale_id.auto_purchase_order_id
	if not purchase:
	continue
	purchase.picking_ids.write({"intercompany_picking_id": pick.id})
	for move_line in pick.move_line_ids:
	qty_done = move_line.qty_done
	sale_line_id = move_line.move_id.sale_line_id
	po_move_lines = sale_line_id.auto_purchase_line_id.move_ids.mapped(
	"move_line_ids"
	)
	for po_move_line in po_move_lines:
	if po_move_line.reserved_qty >= qty_done:
	po_move_line.qty_done = qty_done
	qty_done = 0.0
	else:
	po_move_line.qty_done = po_move_line.reserved_qty
	qty_done -= po_move_line.reserved_qty
	po_picks |= po_move_line.picking_id
	if qty_done and po_move_lines:
	po_move_lines[-1:].qty_done += qty_done
	elif not po_move_lines:
	raise UserError(
	_(
	"There's no corresponding line in PO %(po)s for assigning "
	"qty from %(pick_name)s for product %(product)s"
	)
	% (
	{
	"po": purchase.name,
	"pick_name": pick.name,
	"product": move_line.product_id.name,
	}
	)
	)
	# Transfer dropship pickings
	for po_pick in po_picks.sudo():
	po_pick.with_company(po_pick.company_id.id)._action_done()
	return super()._action_done()

I'll propose a PR with a test confirming this issue and a fix.