[perl #128770] 5334cb725 causes erroneous sink on ($_ with "foo")

[Larry Wall via RT]

The logical ops andthen, notandthen, and orelse were not propagating wantedness 
to their thunky args.

Fixed in 7ba6dbfae97f5ff9398336e49267d51606512df9.

Note that we don't generally test sink warnings currently.