Creating a client with a session using an Unscoped tokens needs to set auth info in client. This Auth Info is necessary in order to enumerate projects. This is the standard login path for Horizon.
This is addressed in the upstream 0.11.2 release of python-keystoneclient. We currently ship 0.11.1 in OSP6. We should rebase to 0.11.2
To verify, you need an unscoped token. This can be done either by removing the default project ID for a user or by using the LDAP backend. Do not set the OS_PROJECT_ID or OS_PROJECT_NAME variables either. The CLI call `openstack project list` should be sufficient. It should succeed with an unscoped token and list the project for the user.
This is not tied to a customer, and is not a problem in the version of Horizon that was reported. This is, instead, a feature that was under development at the time that has been merged upstream.