Re: [PATCH v3 6/7] builtin/maintenance: add a `--detach` flag

> While investigating that, I ran it with --stress locally (on Linux) and
> got some odd (and definitely racy) results. The test itself passes, but
> the "rm -rf repo" in the test_when_finished sometimes fails with:
> 
>   rm: cannot remove 'repo/.git/objects': Directory not empty
> 
> or similar (sometimes it's another directory like 'repo/.git'). My guess
> is that the background process is still running and creating files in
> the repository, racing with rm's call to rmdir().
> 
> Even if we remove the test_when_finished, it would mean that the final
> cleanup after test_done might similarly fail, leaving a crufty trash
> directory. I think to make this robust, we'd need some way of detecting
> when the background process has finished. I don't think we report the
> pid anywhere, and the daemonize() call means it won't even be in the
> same process group. Maybe we could spin looking for the incremental pack
> it will create (and timeout after N seconds)? That feels pretty hacky,
> but I can't think of anything better.