Comment 1 for bug 1515463

Oh yeah, I can see how this is going to be a problem.

I'll look at changing the code path to use auto-detected compression rather than specific one.

The reason for this change in the first place is that the .tar.gz images will be deprecated in favor for .tar.xz, so I'd recommend JuJu also switch to .tar.xz at some point soon (I don't believe the cloud team has set a timeframe for phasing out tar.gz yet, but it's planned).