I don’t think the Eventide Harmonizer had come along at that point, so I’d wager that part is multi-tracked. I hear at least three parts in that, but the intervals are so bizarre I gave up on trying to replicate this part exactly. I can play the rest of this song pretty much note-for-note.
It did sound a bit “Brian Mayish”, but I never heard Gilmour ever do anything like that before or since, it seemed so out of character for him.