improve mocked headers so urllib2 can handle redirects too

vcr/stubs/__init__.py

@@ -17,9 +17,19 @@ class VCRHTTPResponse(object):
         self.version = None
         self._content = StringIO(self.recorded_response['body']['string'])
 
+        # We are skipping the header parsing (they have already been parsed
+        # at this point) and directly  adding the headers to the header 
+        # container, so just pass an empty StringIO.
         self.msg = HTTPMessage(StringIO(''))
+
         for key, val in self.recorded_response['headers'].iteritems():
             self.msg.addheader(key, val)
+            # msg.addheaders adds the headers to msg.dict, but not to
+            # the msg.headers list representation of headers, so
+            # I have to add it to both.
+            self.msg.headers.append("{0}:{1}".format(key, val))
+
+        #self.msg.headers = ["{0}:{1}".format(k,v) for k, v in self.recorded_response['headers'].iteritems()]
 
         self.length = self.msg.getheader('content-length') or None