Comment 3 for bug 1515485

Backtrace in keystone's logs (thanks to Miguel!):

2015-11-12 05:13:34.503 4664 INFO keystone.common.wsgi [-] POST http://172.29.236.100:5000/v3/ec2tokens
2015-11-12 05:13:34.528 4664 ERROR keystone.common.wsgi [-] 'NoneType' object has no attribute 'get'
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi Traceback (most recent call last):
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi File "/usr/local/lib/python2.7/dist-packages/keystone/common/wsgi.py", line 238, in __call__
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi result = method(context, **params)
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi File "/usr/local/lib/python2.7/dist-packages/keystone/contrib/ec2/controllers.py", line 397, in authenticate
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi metadata_ref=metadata_ref)
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi File "/usr/local/lib/python2.7/dist-packages/keystone/token/provider.py", line 344, in issue_v3_token
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi parent_audit_id)
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi File "/usr/local/lib/python2.7/dist-packages/keystone/token/providers/fernet/core.py", line 184, in issue_v3_token
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi if auth_context.get('bind'):
2015-11-12 05:13:34.528 4664 TRACE keystone.common.wsgi AttributeError: 'NoneType' object has no attribute 'get'