Re: [PATCH] Documentation: "bisect run" can be given bangs before the run script.

[Junio C Hamano <junkio@cox.net>]

I am not convinced that '!' is a good extension for two and half
reasons.

 * The expected use is not quite clear.  If it is not used to
   run a custom test script but something stock as "make", by
   the nature of UNIX exit status convention, you are looking
   for the commit that _fixed_ some breakage (i.e. "which commit
   fixed the compilation error?").  While sometimes that is a
   useful thing to do, it feels somewhat of limited value.

   On the other hand, if you are running a custom test script, I
   do not think it is unreasonable to always require that a test
   script to signal "bad" with small non-zero, "good" with zero,
   and error with high non-zero status, as we already do.

 * How should this interact with the "high non-zero status means
   an error and we cannot bisect" return convention?

 * I was hoping that we can officially support "don't know,
   cannot test this one, please give me another" for interactive
   use, and at the same time allow the run-script used by
   "git bisect run" to signal such with a special exit value
   (perhaps "exit 42").  Taken together with the previous point,
   it is not clear how '!' should interact with such an
   enhancement.