API change: service state nodes

[William Reade]

On Fri, 2011-12-16 at 07:14 -0500, Kapil Thangavelu wrote:
> Excerpts from William Reade's message of Thu Dec 15 15:14:23 -0500 2011:
> > As part of the machine constraints story, I propose we add a
> > "constraints" key to the service state nodes' content. This would
> > contain a list of constraint strings because it's convenient and compact
> > and reasonably human-readable (ie we only store the keys that are
> > actually set at the service level, rather than having an explicit
> > fallback/reset/value for every key). So, the node content would look
> > something like:
> > 
> > -------------------------------------------
> > charm: cs:oneiric/mysql-42
> > constraints: [arch=amd64, cpu=, mem=16G]
> > 
> 
> That sounds good, but if the only keys are those stored, what is cpu=?
> 
> cheers,
> Kapil

"cpu=" means "reset CPU to juju defaults, ignore any previous
overrides", as specced.