Three related problems with Drop Shipping with Anglo Saxon Accounting.

One has been broken since #20080.

Another is caused by the same code.

The third - a fix from #12687 - is being bypassed by current code.



Impacted versions:

11.0, and 10.0 for at least some of this

Steps to reproduce:

Set up a product with
- real time valuation
- standard price
- Anglo Saxon accounting
- drop shipping turned on
- invoicing on delivered quantities

Create a product with a standard price of $40.

Current behavior:

_If I create a sales order and choose to ship from existing stock, then the invoice created after delivery is correct, and it has the correct Anglo Saxon account moves._

- Dr COGS $40
- Cr Output $40

If I create a sales order and choose to drop ship, I can then go to the RFQ, and change the RFQ price to $45, then receive the product, and generate the Vendor Bill.  Everything is correct at this point.  When I go back to the Sales Order and create and validate the invoice, it has the incorrect Anglo Saxon account moves:

- Dr Output $45
- Cr COGS $45

Expected behavior:

The accounting should be the same on the invoice.  The value is wrong, and the debits and credits are reversed.

Also, there should be an additional journal:

- Dr Output $40
- Cr Input $40

Th 3 problems are:

1. It is getting a -ve price unit from _compute_average_price because the stock move is not an outgoing move, but a supplier -> customer move!
2. It is getting the average price from those moves and using it, even if the product is using standard price.
3. The extra move that #12687 created is no longer being generated as the account moves are being bypassed entirely for dropshipping.  Somewhere in the process, we need to move the value from stock_input to stock_output.  This may be a v11 problem only.

Video/Screenshot link (optional):


addons/stock_account/models/stock.py
"""
        Generate the account.move.line values to post to track the stock valuation difference due to the
        processing of the given quant.
        """
        self.ensure_one()
        if self._context.get('force_valuation_amount'):
            valuation_amount = self._context.get('force_valuation_amount')
        else:
            valuation_amount = cost
        
        
        debit_value = self.company_id.currency_id.round(valuation_amount)
        
        if self.company_id.currency_id.is_zero(debit_value):
            raise UserError(_("The cost of %s is currently equal to 0. Change the cost or the configuration of your product to avoid an incorrect valuation.") % (self.product_id.name,))
        credit_value = debit_value
        if self.product_id.cost_method == 'average' and self.company_id.anglo_saxon_accounting:
            
            
            
            if self.location_dest_id.usage == 'supplier' and self.origin_returned_move_id and self.origin_returned_move_id.purchase_line_id:
                debit_value = self.origin_returned_move_id.price_unit * qty
            
            
            if self.location_id.usage == 'customer' and self.origin_returned_move_id:
                debit_value = self.origin_returned_move_id.price_unit * qty
                credit_value = debit_value