[FIX] stock: unlink zero quants
[FIX] stock: unlink zero quants

If you create a quant through the inventory mode of the list view and
you don't set a quantity, the quantity is null and the quant isn't
unlinked by _unlink_zero_quants.

Also consider null quantity as 0.

We don't have the issue for the reserved_quantity field since this one
is not nullable.

closes odoo/odoo#48005

X-original-commit: 08e428458aa545b3602c56b6866a447126cf8825
Signed-off-by: Simon Lejeune (sle) <1969d8dff896674c2d819e813f5e88ca826229ab@openerp.com>

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