[FIX] stock: mandatory default source location
[FIX] stock: mandatory default source location

On the picking type form, the default source location is not mandatory
for 'customer' picking types. If this field is empty, creating a
'customer' picking will set a vendor location as source one.

task-1830757

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