Fix #38 -- Return 400 if the given step is not found

[gchp]

No description provided.

[jpic]

LGTM

[jnns]

If a client requests a non-existing step it technically is a BadRequest but there are situations in which it is not the client's fault.

For example, if conditional steps are involved and a condition for a step is not met anymore although a client already began a session in which they are currently at the now missing step NamedURLWizardView.get_form() will raise a KeyError exception.

In this case I personally find it more helpful to redirect the client to the first step than to return a status code 500 (current behaviour) or 400.