fixed master (#6465)

* fixed master

* Revert "Merge pull request #6370 from paritytech/light-poa"

This reverts commit 3c60f99def, reversing
changes made to b731ccea18.

ethcore/light/src/on_demand/mod.rs

@@ -195,8 +195,6 @@ fn guess_capabilities(requests: &[CheckedRequest]) -> Capabilities {
 				caps.serve_headers = true,
 			CheckedRequest::HeaderByHash(_, _) =>
 				caps.serve_headers = true,
-			CheckedRequest::Signal(_, _) =>
-				caps.serve_headers = true,
 			CheckedRequest::Body(ref req, _) => if let Ok(ref hdr) = req.0.as_ref() {
 				update_since(&mut caps.serve_chain_since, hdr.number());
 			},