Fix test_context_middleware py34 error
Fix test_context_middleware py34 error

This was expecting bytes, but stopped working...

The oslo.context change If48ee7f4d1c113f1f26b3b1698c6b055807b950f
changed request_id type on Python 3 from bytes to str.

Change-Id: I9ab47455a0e054714dea5be755cae5ebce9b86d3
Closes-Bug: 1541147

openstack/searchlight,openstack/searchlight,openstack/searchlight