When the MirrorBot runs for the first time, it needs to clone the repository to be mirrored. When doing this, it first creates a directory to clone into, and then attempts cloning. If the cloning fails (or if the bot happens to die at that point), the directory stays around. Then on the next (and all subsequent runs), the bot finds this directory and expects the repo to be present. If it's not, the bot fails.

This needs to be handled better.