[8.0][sale_product_variant_type] new attribue value from so line: missing constraint

[roedeorm]

Place a product template on sale order line that has an attribute "A".
Write into field "Value" in the attribute table in the row or attribute "A" and click create. A window pops up.
The field attribute is empty instead of being prefilled with "A". It has to be filled manually and it is not constrained to "A". All other attribute are a possible selection. This can result in attribute value of a different attribute than attribute "A" created in "A".

Purchase order line has the same issue. Manufacturing order hower works fine.

Tested on
demo.odoomrp.com
dp = September_2015_EN