Add Content-Type header in PushImageLayerRegistry

Docker-DCO-1.1-Signed-off-by: Gabor Nagy <mail@aigeruth.hu> (github: Aigeruth)

registry/registry.go

@@ -522,6 +522,7 @@ func (r *Registry) PushImageLayerRegistry(imgID string, layer io.Reader, registr
 	if err != nil {
 		return "", "", err
 	}
+	req.Header.Add("Content-Type", "application/octet-stream")
 	req.ContentLength = -1
 	req.TransferEncoding = []string{"chunked"}
 	setTokenAuth(req, token)