[FIX] sale_margin: no uom on line.
[FIX] sale_margin: no uom on line.

Since the purchase_price is now computed, it may be triggered before an
uom is set on the product line (onchanges may happen after computes).

closes odoo/odoo#41808

X-original-commit: 9ebbdd24752a0ff1c1057fc533074555810ffa39
Signed-off-by: Victor Feyens (vfe) <433cda6c0f0b5b2dac2ef769109a6da90db60157@odoo.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo