refactor duplicated checks for skipping and fix
refactor duplicated checks for skipping and fix

If you look closely at the diff, you will see that if the product was
defined, the check on make_to_stock was never done. This happens most of
the time.

open-synergy/sale-workflow,factorlibre/sale-workflow,credativUK/sale-workflow,ddico/sale-workflow,xpansa/sale-workflow,BT-jmichaud/sale-workflow,BT-cserra/sale-workflow,adhoc-dev/sale-workflow,jabibi/sale-workflow,jjscarafia/sale-workflow,BT-fgarbely/sale-workflow,akretion/sale-workflow,alexsandrohaag/sale-workflow,brain-tec/sale-workflow,guewen/sale-workflow,richard-willowit/sale-workflow,Antiun/sale-workflow,akretion/sale-workflow,brain-tec/sale-workflow,VitalPet/sale-workflow,luistorresm/sale-workflow,kittiu/sale-workflow,diagramsoftware/sale-workflow,grap/sale-workflow,damdam-s/sale-workflow,Rona111/sale-workflow,clubit/sale-workflow,acsone/sale-workflow,anybox/sale-workflow,numerigraphe/sale-workflow,Eficent/sale-workflow,numerigraphe/sale-workflow,thomaspaulb/sale-workflow,anas-taji/sale-workflow,acsone/sale-workflow,Endika/sale-workflow,BT-ojossen/sale-workflow,fevxie/sale-workflow,kittiu/sale-workflow