And remove machine-id-commit as separate binary.
There's really no point in keeping this separate, as the sources are
pretty much identical, and have pretty identical interfaces. Let's unify
this in one binary.
Given that machine-id-commit was a private binary of systemd (shipped in
/usr/lib/) removing the tool is not an API break.
While we are at it, improve the documentation of the command substantially.
Even trivial service occasionally get stuck, for example when
there's a problem with the journal. There's nothing more annoying
that looking at the cylon eye for a job with an infinite timeout.
Use standard 90s for jobs that do some work, and 30s for those which
should be almost instantenous.
The unit file only active the machine-id-commit helper if /etc is mounted
writable and /etc/machine-id is an independant mount point (should be a tmpfs).
Zbigniew Jędrzejewski-Szmek