worker/provisioner: no tools is an error

worker/provisioner: no tools is an error

We were treating no tools found as an error of the Provisioner, rather
than an error with the machine we were trying to provision (bug
#1311676). This now sets the status of the machine to an error state,
which lets us continue with our lives.

In the original bug about not having tools, it was shown that in the
local provider, doing

  juju bootstrap -e local
  juju deploy -e local precise/ubuntu
  juju deploy -e local trusty/ubuntu ubuntu-t

Would end up with both machines stuck in Pending. Now it says:
$ juju status -e local
environment: local
machines:
  "0":
    agent-state: started
    agent-version: 1.18.2.1
    dns-name: localhost
    instance-id: localhost
    series: trusty
  "1":
    agent-state-info: '(error: no matching tools available)'
    instance-id: pending
    series: precise
  "2":
    agent-state: started
    agent-version: 1.18.2.1
    dns-name: 10.0.3.194
    instance-id: jameinel-local-machine-2
    series: trusty
    hardware: arch=amd64

And you can see that it succeeded in deploying trusty because it put
precise into an error state.

https://code.launchpad.net/~jameinel/juju-core/1.18-provisioner-no-tools-is-fatal-1311676/+merge/217011

(do not edit description out of merge proposal)

[jameinel, 2014-04-24 09:31:35]

Please take a look.

[natefinch, 2014-04-24 09:52:02]

LGTM

[fwereade, 2014-04-24 10:11:19]

LGTM if either use the existing method or have some good reason why it's
unsuitable.

https://codereview.appspot.com/93720044/diff/1/worker/provisioner/provisioner...
File worker/provisioner/provisioner_task.go (right):

https://codereview.appspot.com/93720044/diff/1/worker/provisioner/provisioner...
worker/provisioner/provisioner_task.go:423: if err1 :=
machine.SetStatus(params.StatusError, err.Error(), nil); err1 != nil {
isn't there a setErrorStatus method already?