I saw this growing at the ex-job, out on the nursery lot. It wasn't for sale, because it wasn't in a pot, and it didn't look like it had been deliberately planted, but it's also very odd and passably-ornamental looking, so I suppose it could have been an escapee. I don't recall us ever selling potted morning glories (moonflowers, yes, but not morning glories), though, nor did we ever offer sweet potato vines with this sort of variegation. So . . . what is it?
It was late afternoon when I took these pictures. The plant was in a location that likely gets only afternoon sun, and not very much of it: there are some fairly dense trees growing overhead.