lock: pass "success" boolean to _afterlock callbacks This lets the callback decide if it should actually run or not. I suspect that most callbacks (and hooks) *should not* run in this scenario, but I'm trying to not break any existing behavior. `persistmanifestcache`, however, seems actively dangerous to run: we just encountered an exception and the repo is in an unknown state (hopefully a consistent one due to transactions, but this is not 100% guaranteed), and the data we cache may be based on this unknown state. This was observed by our users since we wrap some of the functions that persistmanifestcache calls and it expects that the repo object is in a certain state that we'd set up earlier. If the user hits ctrl-c before we establish that state, we end up crashing there. I'm going to make that extension resilient to this issue, but figured it might be a common issue and should be handled here as well instead of just working around the issue. Differential Revision: https://phab.mercurial-scm.org/D7459