[FIX] stock: unable to return SN in chained moves

Use case to reproduce the bug:
- Set multi location in settings
- Set warehouse's deliery method as pick/pack/ship
- Deliver a product to customer
- Process a return from customer to output.
- Create a return from output to pack ->
Unable to reserver product.

It happens because return moves where not linked together but have
the picking that created the return as origin.
Thus action_assign does not detect the return moves and can't
guess the real quantity available.

This commit add a behavior that will create links between
return move. It can be guess from parent move(the picking's move from which
the return is created) and its move dest/orig that have already
created other return. It also correct action assign because
the group by could retourn same line with return moves.
It add a test that check returns and links between them.

0 files changed, 0 insertions, 0 deletions