You are correct. It was on the For Sale demo along with Slumming It With Johnny, which we're both released after IARB. This album is just pre-IARB stuff.
Actually, "But a Fleeting Illness" was not on the For Sale EP. It was released as a demo on Doghouse Record's Spring/Summer 2003 sampler. One of their best songs that didn't make it on IARB.