Clicking synchronize on `/queue/all` gives an error

[Manishearth]

  File "/home/servo/homu/_venv/bin/bottle.py", line 862, in _handle
    return route.call(**args)
  File "/home/servo/homu/_venv/bin/bottle.py", line 1732, in wrapper
    rv = callback(*a, **ka)
  File "/home/servo/homu/homu/server.py", line 103, in callback
    repo_cfg = g.repo_cfgs[repo_label]