POST with empty body results in error

[srekke]

I encountered an error when trying to proxy a POST without body, because in that case the Content-Length is not being set:

12:02:54 web.1 | [Rack::StreamingProxy] Parent process 62926 forked a child process 62927.
12:02:54 web.1 | [Rack::StreamingProxy] Child starting request to http://127.0.0.1:3600/messages/29/read.json
12:02:54 web.1 | [Rack::StreamingProxy] Child process 62927 passing on ArgumentError: Content-Length not given and Transfer-Encoding is not `chunked'
12:02:54 web.1 | [Rack::StreamingProxy] Child process 62927 closing connection.
12:02:54 web.1 | [Rack::StreamingProxy] Parent received unexpected nil status!
12:02:54 web.1 | [Rack::StreamingProxy] Child process 62927 exiting.
12:02:54 web.1 | [Rack::StreamingProxy] Parent process 62926 waiting for child process 62927 to exit.
12:02:54 web.1 | App 62909 stderr: Rack::StreamingProxy::UnknownError

Thank you for this middleware by the way. :)
Best regards,
Steven