Stateful commits, "revert previous"

[maya%netbsd.org@localhost]

> Log Message:
> Revert previous
> 
> There is fallout in gdb that will be investigated before relanding this.
> 
> 
> To generate a diff of this commit:
> cvs rdiff -u -r1.363 -r1.364 src/sys/kern/kern_sig.c
> 

Looking at this file on GitHub's history it looks like:

Revert previous
2 days ago

Enhance reliability of ptrace(2) in a debuggee with multiple LWPs
2 days ago

Eliminate PS_NOTIFYSTOP remnants from the kernel 
2 days ago

It's hard to tell whether you reverted both, or just the last one.

It would be nice if, in general, we avoided stateful commit messages
like this, and included a snippet of the original commit message.

e.g. Revert previous "Enhance reliability of ptrace(2) in a ..."