buildsys: killing "waiting" jobs?

[Ville Skyttä]

Just out of general interest, is there a way to remove a queued build
when it's in the "waiting" state?

"plague-client kill <jobid>" for a waiting job says it succeeded, but no
changes are reflected in the buildsys web UI.  The job stays in
"waiting" state there, and a subsequent requeue fails saying the job
needs to be killed or failed before requeuing.