Fix product_by_location with stock_skip_warehouse and no product_ids

issue3843
review5171002
(grafted from f2f79e388f07fede7be1273ad1e64477a78eaadf)

--HG--
branch : 3.0
extra : source : f2f79e388f07fede7be1273ad1e64477a78eaadf
extra : amend_source : c1baa808c71b74634819975fa79fd4d7ff516a87
Prepare release 3.0.2

--HG--
branch : 3.0
Added tag 3.0.2 for changeset b6ce2186c690

--HG--
branch : 3.0
Increase version number

--HG--
branch : 3.0