Rabbi Tzvi Hirsh of Zidichov emended the passage from Tractate Soferim from "habechorot mit’anin b’erev pesach" (“the firstborn fast on Erev Pesach”), but "habechorot mit’an’gin b’erev pesach" (“the firstborn indulge on Erev Pesach”)(Zimmels, HJ. Ashkenazim and Sephardim). This is presumably a homiletic treatment. An actual emendation is not likely given the context of the passage, nor is an emendation widely accepted halakhically.
hirhurim.blogspot.com
See here and here for more discussion on the adjusted fast and its ramifications
