After migrating to LDAP, instances no longer start.

Issue

After migrating to LDAP for assignment and identity, instances fail with this error in /var/log/nova/nova-compute.log:

2014-10-27 15:06:54.522 19283 TRACE nova.compute.manager [instance: fa99331c-452b-4b05-978a-2dd6634e45a6] VirtualInterfaceCreateException: Virtual Interface creation failed

Upon further inspection, these additional errors were noted in /var/log/keystone/keystone.log:

2014-10-27 15:06:59.114 28475 WARNING keystone.token.controllers [-] User nova is unauthorized for tenant a224b9439a2a4ab5b9d95e118179491f

and /var/log/neutron/server.log:

2014-10-27 15:06:59.119 18631 TRACE neutron.notifiers.nova Unauthorized: User nova is unauthorized for tenant a224b9439a2a4ab5b9d95e118179491f (HTTP 401)