[FIXED JENKINS-29568] A better fix

- 252e1296 doesn't work for all cases as there are code paths
  where a pending launch can be removed from the pending list and not have spent() called.
- There was no reason for iterating the list twice anyway, as all of this takes place with the locks held
- My notifying each one as we process, if there is an Error, we will not leave any stranded. The next run
  through, if there is one, will cover those instances.