Settings nav method can call attempt access of slug on None

[David Lyle]

When adding tests to horizon, it's possible to encounter an error in dashboards/settings/dashboard.py where the current dashboard is not set. Then the slug attribute is attempted to be accessed on None. Doesn't work real well :)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/79769

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/79769
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=ab3cdfd1c90039a126f8310c3d57847bf95542ea
Submitter: Jenkins
Branch: master

commit ab3cdfd1c90039a126f8310c3d57847bf95542ea
Author: David Lyle <email address hidden>
Date: Tue Mar 11 15:04:52 2014 -0600

    Fixing potential attribute access on None

    Specifically when writing tests, the nav method in the settings
    dashboard.py file can potentially attempt to access slug on None.

    Closes-bug: #1291050

    Change-Id: I6df58d26f5df71ac7c605c5d77b9aa9d8d811956