Fix feed rendering

[hannesbochmann]

#734

[okmiim]

Hi @hannesbochmann,
thank you for the contribution and investigation.
You are actually right with $response->getBody()->__toString() (or event better with rewind()).
The other problem (with my other test-implementations) were wrong response codes on pages with multiple actions.

I will not merge your PR in favor of e7af8ba, since I made some other improvements (PropagateResponseException). But still, through your contribution I found the "blocking error" 😉 .

[hannesbochmann]

Glad I could help and thanks for your effort :-)