If a nightly build is run and the child targets triggered, killing them is a painful procedure. There should be a kill button, that kills the trigger build and all children from it. Or at least make this a bit more elegant.
It appears upstream did work on fixing this, https://github.com/buildbot/buildbot/commit/e500b39d7f17c83847f89a3648b3464babb935dc/Buildbot so if we upgrade buildbot, this might even be fixed...
Fixed. Patch is in master and production.