manifestcache: skip setup earlier if we don't have the lock There a no point preparing a closure if we are not going to use it.

manifestcache: test the cache is warm after a commit

manifestcache: stop altering the lru cache order while displaying it Accessing value with `.get` alter the iteration order and make the output of the debug command misbehave, showing multiple entry twice. We need more than 2 entry to see the bug, so there are not test change. Later test will introduce a third entry and would fail without this fix.