upgrade fails if no explicit version is specified

[Ian Booth]

The scenario was that a user was running 1.20.14 and using a 1.22.1 client, ran upgrade-juju.
Juju claimed that "no upgrades available". However, tools were there:

$ juju metadata validate-tools
Matching Tools Versions:
- 1.22.1-trusty-amd64
- 1.22.1-trusty-arm64
- 1.22.1-trusty-armhf
- 1.22.1-trusty-i386
- 1.22.1-trusty-ppc64el
Resolve Metadata:
  source: default simplestreams
  signed: false
  indexURL: https://streams.canonical.com/juju/tools/streams/v1/index2.json
  mirrorURL: https://juju-dist.s3.amazonaws.com/tools

Explicitly specifying the version using --version worked.

It appears upgrades might still be trying to just increment the minor version by 1 when automatically figuring out what to upgrade to, instead of upgrading to the latest. There's also incorrect help text around this legacy behaviour.

[Jesse Meek (waigani)]

PR: http://reviews.vapour.ws/r/1914/

[Mario Splivalo (mariosplivalo)]

FWIW, this is still an issue when upgrading to 1.24.5.

[Ian Booth (wallyworld)]

The fix for this issue has landed in 1.25.
Earlier releases will not have the fix.