[PATCH 1 of 7] blackbox: log working directory version

[timeless]

Durham Goode wrote:
> Does this mean every hg command will be running 'hg status' under the hood
> to populate the '+'?  And is it happening for every ui.log() as well, when
> the blackbox is enabled?
>
> If that's the case, that would introduce some major perf issues I think.

Yes. It's only doing the `+` stuff because I was asked to do it.
There's /some/ value in knowing dirty state, but perhaps a better
approach would be for blackbox to monitor status and log when
something reports dirty state instead of checking constantly.

I'm not wed to the `+`.
I'd rather get as much of this series in as possible, than get stuck
on any particular corners.