Re: [PATCH] t/README: clarify test_must_fail description

On Tue, Jul 20, 2010 at 18:00, Junio C Hamano [off-list ref] wrote:

   Run a git command and ensure it fails in a controlled way.  Use
   this instead of "! <git-command>".  When git-command dies due to a
   segfault, test_must_fail diagnoses it as an error; "! <git-command>"
   treats it as just another expected failure. letting such a bug go
   unnoticed.

To add to that:

    Don't use test_must_fail to negate the return values of commands
    on the system like grep, sed etc. If we can't trust that the core
    utilities won't randomly segfault we might as well die horribly.