sectionactions create() should sanitise input for create_from_object(). create() generally takes a section number of 0 to mean the end of the course, where ever it may be, whereas create_from_object() uses an unset section number for this purpose. (Specifying 0 for end doesn't work with create_from_object()--the new section is left at the very end, even if it's a non-delegated section.) However, if skipcheck is set, a section number of 0 given to create() must actually mean 0, because in this case the section number is to be taken as given, both for the initial creation position and the final position.

This fix is included in MDL-82941, but I thought I ought to submit it separately.