tests: BlockwiseFileset tests call close() when they are finished.
request_rewrite changes:
- Don't autosubmit in notify_finished
- Allow finished callbacks to call wait() on their own request, even though this is a little silly.
  (This was already working in request contexts, but now it works in foreign thread contexts, too)
- Fixed import issue for RequestLock.
tests: request_rewrite: Disable trace logging.