My build is stuck on "Queued" and never processing

My build https://travis-ci.org/github/pioneers/c-runtime/builds/711600882 is just not starting and stuck in “Queued”. I’ve seen this happen before and sometimes if I cancel and restart it, it will boot up the VM properly. This time, that doesn’t seem to work. I’ve made sure that I have no other concurrent builds that could block this one. Any help/suggestions?