Lowercase all thrift headers for compatibility with http

Author: honzakral

elasticsearch/connection/thrift.py

@@ -75,5 +75,8 @@ def perform_request(self, method, url, params=None, body=None, timeout=None, ign
  self.log_request_success(method, url, url, body, response.status,
  response.body, duration)
 
- return response.status, response.headers or {}, response.body
+ headers = {}
+ if response.headers:
+ headers = dict((k.lower(), v) for k, v in response.headers.items())
+ return response.status, headers, response.body