Broken MultiSignature verification for ECDSA keys

[akru]

Looks like Verify instance will not works for ECDSA because this instance recover the compressed public key:

https://github.com/paritytech/substrate/blob/master/primitives/runtime/src/lib.rs#L311

(MultiSignature::Ecdsa(ref sig), who) => {
	let m = sp_io::hashing::blake2_256(msg.get());
	match sp_io::crypto::secp256k1_ecdsa_recover_compressed(sig.as_ref(), &m) {
		Ok(pubkey) =>
			&sp_io::hashing::blake2_256(pubkey.as_ref())
				== <dyn AsRef<[u8; 32]>>::as_ref(who),

But ecdsa module uses the uncompressed public key for AccountId derivation:

https://github.com/paritytech/substrate/blob/master/primitives/core/src/ecdsa.rs#L51
https://github.com/paritytech/substrate/blob/master/primitives/runtime/src/lib.rs#L249