version: tests fail on arm64 14.04

[Dave Cheney]

FAIL: supportedseries_linux_test.go:17: supportedSeriesSuite.TestSeriesVersion

supportedseries_linux_test.go:26:
    c.Assert(err, jc.ErrorIsNil)
... value *errors.Err = &errors.Err{message:"", cause:"precise", previous:"precise", file:"github.com/juju/juju/version
/supportedseries.go", line:195} ("unknown version for series: \"precise\"")
... error stack:
        unknown version for series: "precise"
        github.com/juju/juju/version/supportedseries.go:195:

OOPS: 23 passed, 1 FAILED
--- FAIL: Test (0.34s)
FAIL
FAIL github.com/juju/juju/version 0.540s

How is this even possible???

[Dave Cheney (dave-cheney)]

This is caused by this helpful footgun

// updateDistroInfo updates seriesVersions from /usr/share/distro-info/ubuntu.csv if possible..
func updateDistroInfo() error {
        // We need to find the series version eg 12.04 from the series eg precise. Use the information found in
        // /usr/share/distro-info/ubuntu.csv provided by distro-info-data package.
        f, err := os.Open(distroInfo)
        if err != nil {
                // On non-Ubuntu systems this file won't exist but that's expected.
                return nil
        }
        defer f.Close()
        bufRdr := bufio.NewReader(f)

If /usr/share/distro-info/ubuntu.csv is missing, then we quietly pretend like there are NO UBUNTU SERIES EVER!!!

[Ian Booth (wallyworld)]

The above comment is not true - the updateDistroInfo() is used to update a pre-populated map of series->version. It augments what is known by Juju at the time the code was compiled with any more recent data.