juju upgrade-juju - major version upgrades

juju upgrade-juju - major version upgrades

Previously, juju upgrade-juju rejected
major version upgardes. They are now        
allowed, with some other changes.

1. No version specified

If the CLI major version > agent major version,
then the target version for upgrade is the
CLI version. 
Where CLI major version = agent major version, then
the minor version is bumped to the next stable 
release version as happens now.

2. Minor version downgrades not supported

Tools matching has already been changed to match
on major.minor, and the new upgrade infrastructure
only supports upgrading, so we should disallow
downgrades.

https://code.launchpad.net/~wallyworld/juju-core/enable-major-upgrades/+merge/209378

(do not edit description out of merge proposal)

[wallyworld, 2014-03-05 07:03:01]

Please take a look.

[fwereade, 2014-03-06 15:06:43]

LGTM

https://codereview.appspot.com/69890053/diff/1/cmd/juju/upgradejuju.go
File cmd/juju/upgradejuju.go (right):

https://codereview.appspot.com/69890053/diff/1/cmd/juju/upgradejuju.go#newcod...
cmd/juju/upgradejuju.go:357: v.agent.Major, v.agent.Minor, v.chosen.Major,
v.chosen.Minor)
`%s to %s", v.agent, v.chosen`?

[wallyworld, 2014-03-06 21:48:10]

https://codereview.appspot.com/69890053/diff/1/cmd/juju/upgradejuju.go
File cmd/juju/upgradejuju.go (right):

https://codereview.appspot.com/69890053/diff/1/cmd/juju/upgradejuju.go#newcod...
cmd/juju/upgradejuju.go:357: v.agent.Major, v.agent.Minor, v.chosen.Major,
v.chosen.Minor)
On 2014/03/06 15:06:43, fwereade wrote:
> `%s to %s", v.agent, v.chosen`?

I was wanting to only include major.minor in the error message because that's
what the decision was based on. But perhaps we should just print the full
version. I've changed it.