Unit state during charm upgrade

[Clint Byrum]

Excerpts from Gary Poster's message of Mon Mar 05 08:27:11 -0800 2012:
> On 03/05/12 11:22, Benji York wrote:
> > On Mon, Mar 5, 2012 at 11:10 AM, Gary Poster<gary.poster at canonical.com>  wrote:
> >> With Francesco's proposed change, the test does this.
> >> - start upgrade
> >> - loop until the status is no longer "updating".  If we never see the
> >> "updating" status that's fine: it must have been a fast update, but now we
> >> know we are ready to test the result of the update.
> >
> > The above would work as long as the command to start the upgrade doesn't
> > return until the state transition from "running" to "updating" takes
> > place.  In other words, this sequence of events should not be possible:
> >
> > - upgrade is initiated
> > - juju status shows "running"
> > - juju status shows "upgrading"
> > - juju status shows "running"
> 
> Agreed.  Another alternative is that the version number does not change 
> until the "upgrading" status displays; then we can check for the new 
> version number & "running".  Only slightly more to do in the test loop.

I think the only logical thing is to display the charm version that is
actually running, and the new charm is not actually running until after
upgrade-charm has been executed and completed.