Keep body if request uses chunked TransferEncoding

Fixes #151

handler/proxy_client.go

@@ -149,7 +149,11 @@ func (p *ProxyClient) Do(req *http.Request) (*http.Response, error) {
 	// to magically set Transfer-Encoding: chunked. Service like S3 does not support chunk encoding.
 	// We need to manipulate the Body value after signv4 signing because the signing process wraps
 	// the original body into another struct, which will result in Transfer-Encoding: chunked being set.
-	if proxyReq.ContentLength == 0 {
+	//
+	// If the original request has the outermost "chunked" TransferEncoding, do
+	// not remove the body as the ContentLength header will then be missing
+	// (which Go reports as a length of 0).
+	if proxyReq.ContentLength == 0 && !(len(req.TransferEncoding) >= 1 && req.TransferEncoding[0] == "chunked")  {
 		proxyReq.Body = http.NoBody
 	}