enabling use-https or https-service-endpoints once either has already been enabled gets ignored

The config-changed hook defers ssl-related config to the cluster relation-changed-hook if num units > 1. Currently the trigger used remains the same once set so if you first enable one of use-https or https-service-endpoints then at some later stage enable the other, the cluster relation hook will not fire.

Note that this is not a problem if enabling both at once and use-https is a subset of https-=service-endpoints anway so the only real transition that produces a problem is:

use-https=no + https-service-endpoints=false => use-https=yes + https-service-endpoints=false => use-https=yes + https-service-endpoints=true

I will look to getting this fixed and backported as soon as 15.01 is cut.