aiohttp headers are case insensitive (#461)

* aiohttp headers are case insensitive

* flakes

tests/integration/test_aiohttp.py

@@ -59,12 +59,24 @@ def test_headers(tmpdir, scheme, auth):
             request = cassette.requests[0]
             assert "AUTHORIZATION" in request.headers
         cassette_response, _ = get(url, auth=auth)
-        assert cassette_response.headers == response.headers
+        assert dict(cassette_response.headers) == dict(response.headers)
         assert cassette.play_count == 1
         assert 'istr' not in cassette.data[0]
         assert 'yarl.URL' not in cassette.data[0]
 
 
+def test_case_insensitive_headers(tmpdir, scheme):
+    url = scheme + '://httpbin.org'
+    with vcr.use_cassette(str(tmpdir.join('whatever.yaml'))):
+        _, _ = get(url)
+
+    with vcr.use_cassette(str(tmpdir.join('whatever.yaml'))) as cassette:
+        cassette_response, _ = get(url)
+        assert "Content-Type" in cassette_response.headers
+        assert "content-type" in cassette_response.headers
+        assert cassette.play_count == 1
+
+
 def test_text(tmpdir, scheme):
     url = scheme + '://httpbin.org'
     with vcr.use_cassette(str(tmpdir.join('text.yaml'))):

vcr/stubs/aiohttp_stubs/__init__.py

@@ -7,6 +7,7 @@ import logging
 import json
 
 from aiohttp import ClientResponse, streams
+from multidict import CIMultiDict, CIMultiDictProxy
 from yarl import URL
 
 from vcr.request import Request
@@ -61,7 +62,7 @@ def build_response(vcr_request, vcr_response, history):
     response.status = vcr_response['status']['code']
     response._body = vcr_response['body'].get('string', b'')
     response.reason = vcr_response['status']['message']
-    response._headers = vcr_response['headers']
+    response._headers = CIMultiDictProxy(CIMultiDict(vcr_response['headers']))
     response._history = tuple(history)
 
     response.close()