It isn't obvious (your patch fot ret value). Why are you hiding all codes except E_FAIL? Tests are needed, but I think you're hiding something by this change.
Please, clarify, what patch are you trying to blame: (1) [2/3] oleaut32: return correct error code. or (2) gdiplus: IPicture_SaveAsFile updates seek pointer, so put it back.
Both of them are obvious and are not hiding anything. On the contrary, (1) reveals hidden bug in another module (gdiplus), and (2) fixes that bug.
-- Kirill