[FIX] stock: incorrect quantity in the past

[mwath]

Steps to reproduce:

1. Create a storable product and set the quantity on hand to 100 units
2. Create a delivery of 20 units and mark as to-do
3. In the detailed operations, change the quantity to 10 units
4. Validate the transfer without backorder
5. Go to Inventory > Reporting > Locations
6. Click on Inventory at Date, and select a date one month in the past
7. The on hand quantity for the product is 10

Before this commit:

When viewing a product's quantity in the past, the value was based on the product_qty of the done stock moves. However, this is the demand, and it is not always equals to the quantity that moved.

After this commit:

Use the quantity of the done stock move lines, which reflect better what really moved in the past.

opw-3946354

[robodoo]

.

[clesgow]

Suggested change

	moves_in_res_past = {product.id: product_qty for product, product_qty in MoveLine._read_group(domain_move_in_done, ['product_id'], ['quantity:sum'])}
	moves_out_res_past = {product.id: product_qty for product, product_qty in MoveLine._read_group(domain_move_out_done, ['product_id'], ['quantity:sum'])}
	moves_in_res_past = {product.id: product_qty for product, product_qty in Move._read_group(domain_move_in_done, ['product_id'], ['quantity:sum'])}
	moves_out_res_past = {product.id: product_qty for product, product_qty in Move._read_group(domain_move_out_done, ['product_id'], ['quantity:sum'])}

Why not use the quantity field from moves directly?

[mwath]

That should work in theory, but the location might not be the same on the move and the move line.
The move line should have a child location of the move, but there are no restriction on the usage of the child location; You can make a move line with 5 qty in WH/Stock and another 5 qty in WH/Stock/Scrap in the same stock move.

It's not the best workflow, but I've seen some users do weird stuff like that before.
Actually, this config might not even work properly, quants on hands include WH/Stock/Scrap. So we could consider using the move directly, as it should work in most cases.

[clesgow]

Thanks!
@robodoo r+