Comment 1 for bug 1654847

Looks like we need to add X-Service-Token to the list of headers we hash:

  secure_headers = ('authorization', 'x-auth-token',
                          'x-subject-token',)

https://github.com/openstack/keystoneauth/blob/f345559a06c0128dcb7fede4b593487540da86ef/keystoneauth1/session.py#L289-L290