Travis stuck on build but doesn't die, long past the timeout deadline

originally reported here:

This build has been stuck for quite a long time (so other PRs have been stuck in the queue for a long time)
It should’ve timed out but didn’t (was long past the timeout deadline) and it affected queued jobs.

note: a commit was force pushed, overwriting the commit that was used for that stuck build
the build was manually killed, but we’re wondering why it wasn’t automatically killed after timeout