[FIX] point_of_sale: handle returns always correctly

We support 'returns' in the POS frontend by allowing the user to
specify a negative quantity. Before this patch however, the backend
would always generate a single picking per pos.order. This is
problematic when a pos.order contains both lines with a positive and
negative quantity. The generated move lines would not all have the same
source and destination location and so could not be added to the same
picking.

This commit creates an extra 'return' picking when required and assigns
the generated moves to the correct picking.

opw-690812

Closes #13929

Forward-port of 19cca50e7c8d7e6b86f3851398725ce64694b063

0 files changed, 0 insertions, 0 deletions