users must be able to cancel their own runs
Right now, if you try and kill a teuthology run, you can't without special permissions. On ovh it demands your password for sudo (which is tons of fun since I don't think any of the user accounts have passwords, just keys) to kill it. On sepia you need to have passwordless ssh to the remote nodes in order for it to invoke teuthology-nuke properly, which only the ubuntu account has access to.
Obviously, this can cause trouble if you're trying to clean up a dead or otherwise broken run.