When creating an extra move, the price_unit field was not copied. It is
normal since the field is copy=False following rev[0].
But there was a side effect: let's say you order 1 product @ $10 and you
receive 5. The received quantity field on the purchase order line is
correctly set to 5 and the valuation inside the stock is correctly set
at $50, but on the picking there is one move line of 5 and a move a 4
and of 1, instead of one of 5. Note that in v10, the pack operation
would be split between the original move and the extra move, but in our
case the extra move is merged back in the original move, so we don't
need to split the move line. The split mechanism is there only when
working with moves without picking[1].
The issue here is that the moves are not merged because they do not have
the same price unit (5 and 0). We thus copy the unit price when creating
the extra move.
When creating a backorder, the price_unit field wasn't copied either.
It's not important when working with the classic flows (the link to
purchase_line_id is kept), but to be consistent we also copy it.
[0] https://github.com/odoo/odoo/commit/a4740861d3fdbecc8b1171b7d2072697e8a36258
[1] https://github.com/odoo/odoo/commit/561b3461a020021d911999cb41154f158b069a1d
Simon Lejeune
3c03376733