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

originally reported here: https://github.com/nim-lang/Nim/issues/10013

This build has been stuck for quite a long time https://travis-ci.org/nim-lang/Nim/builds/468568083 (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

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