If hardware changes (or charm changes) and we want to remove a check, the charm doesn't do so

[Xav Paice]

When fixing lp1819733, I came about the situation where install() provides a different list of tools to the one already stored by kv.set('tools', list(tools)) on a previous iteration. New checks would have been added, but the one I wanted removed wasn't removed. We need to include some read of the 'old' value and check if there's a difference, if there is then we want to remove the old checks.

Suggest adding a kv.get('tools', set()) just before the kv.set, and then checking the difference, using remove_nrpe_checks() to remove the differences.

[Eric Chen (eric-chen)]

Close very old issue