I seem to have this working with our hostname, and a subsequent destroy and an up, so I'll put up a PR.
Created attachment 8588673 [details] [review] treeherder-service-PR#449 Please see above PR for status and review. (will add Ed when he's back an accepting r?'s).
Commit pushed to master at https://github.com/mozilla/treeherder-service https://github.com/mozilla/treeherder-service/commit/5a7d59e03a9b2d6065ac691fdaf4efb1ac98750d Bug 1089639 - Add treeherder hostname to Vagrantfile for a clean up
Marking fixed per above merge.