final leadership switch

[fwereade]

This is a vast diff, containing everything in RB2229, RB2255, and RB2281; bringing master up-to-date with the status fixes and leadership changes landed in 1.24 already.

It wasn't an entirely clean merge, but nor were the changes particularly challenging. I would appreciate confirmation that the StatusAllocating logic in master is correct, and that it's correct for me to tag the upgrade step with the version for which it was introduced (1.24.4) despite the fact that some other state upgrade steps for 1.24.x have mysteriously migrated to 1.25 (someone else is looking into this, FWIW).

It's also notable in that it's a net reduction of over 1000 lines of code, which isn't something you get to do every day.

(Review request: http://reviews.vapour.ws/r/2289/)

[dimitern]

Merging on by request of fwereade.
$$merge$$

[jujubot]

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju

[jujubot]

Build failed: Does not match ['fixes-1479289']
build url: http://juju-ci.vapour.ws:8080/job/github-merge-juju/4194

[dimitern]

JFDI
$$merge$$
The fix for the blocker bug http://pad.lv/1479289 depends on this change.

[jujubot]

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju