PSA: juju/utils/set/{Strings, Tags} cannot be used without initalisation

[David Cheney]

Hello,

If you use set.Strings, or set.Tags, please be aware of this issue

https://github.com/juju/utils/pull/84

The underlying problem is the lazy initialisation would not work in
all cases and could cause data written to a set to be dropped. Please
refer to the pull request for details.

The code has been changed to panic if this unsafe condition is encounted

The fix in code (which i'll land in a followup branch) is to replace

var s set.Strings
s.Add("something")

with

s := set.NewStrings()

Cheers

Dave