I’ve gotten bugzilla to run acceptably well on Heroku. Still no memcached support (I need to work on my patch for that a little bit more and then add support to bugzilla for it) but I’m pretty happy with this.

Until I take it down, here is a working Bugzilla 5.1.1+ install on heroku, fronted by fast.ly. Emails works, so it is possible to create new accounts.
https://calm-sands-84076-herokuapp-com.global.ssl.fastly.net/