Could you please file a PR with as much information you can get next 
time you get a crash? I will work on it then.
I guess compiling vi with DBG=-g and installing it unstripped (as is 
the default on -current now) will get you a useful backtrace.

Thanks,
  Aymeric

Herb Peyerl wrote:

> off topic but related.  Is anyone else seeing random and 
> un-reproducible
> SEGV's with 'nvi' in multi-buffer mode, most often when yanking and 
> pasting
> from one buffer to another?
>
> It happens frequently enough that it's annoying but infrequently enough
> that it's hard to reproduce.