Comment 16 for bug 1491131

@shihanzhang, some of the points were already fixed in liberty, is there something deserving a backport?.

I would add a sanity check on ipset delete to make sure we don't permanently blow up the agent, but dumping some sort of ugly error we could trace back via log stash.

Said that, the ipset delete for a non existing ipset didn't show up in log stash last time I looked for it.