Some combination of this new build and a new laptop (:-) have cured
 the ediff problems I reported last week [1] -- thanks. 
The regression fix is almost certainly the cure that caused this.
 
 The regexp/stack overflow/crahs-and-burn problem [2] remains. 
Bother, I meant to release the kit with REGEX_MALLOC defined as an
experiment. I'll give it a spin the next time I do a release.
andy