Try reverting https://github.com/mamedev/mame/commit/3bb6c2b58656f8afedb3a1f6a69280adf957bd1b
. Otherwise try finding out that last version that worked.
Edit: Just tried my old install of 1.0, didn't work until I realized I hadn't set the MMU properly then it booted fine. Even if that isn't the problem you (maybe it's a 1.2 specific issue) we probably ought to put a writeup somewhere for people who want to try it out.