This came up last week with the OpenStack provider with issue https://github.com/fog/fog/pull/2578. 

It looks like you have already discovered that `response.headers` is case sensitive. We need to update this [line](https://github.com/fog/fog/blob/master/lib/fog/rackspace.rb#L125) to use `get_headers` as well. Can you fix this and revert line 121?