executor.git.remote.update()

[kurtbrose]

    executor.git.remote.update(
AttributeError: 'functools.partial' object has no attribute 'update'

Also, even if we have to make a whole other class, I think we should definitely give a clear error message. "foo is a leaf-command and cannot have sub-commands (tried to access bar)"... I don't know exactly, but functools.partial attribute error is really awful for a very easy-to-make mistake.