i eventually gave up (sdcc would generate 0x20-long records on debian and 0x10-long records on nixos and there aren't any patches in either of them and the lengths should have been compile time defines) and wrote a normalizing script because i was not prepared to spend my day doing this shit
debian actually carries one patch: it fixes a typo in the source code and two in the changelog, changes nothing else. clear sign of too much time on one's hands