Stable backports (#8055)

* CI: Fix cargo cache (#7968)

* Fix cache

Blocking waiting for file lock on the registry index

* Only clean locked cargo cache on windows

* fixed ethstore sign (#8026)

* fix cache & snapcraft CI build (#8052)

after successful testing it is necessary to port in a ```beta``` and ```stable```

*  Add MCIP-6 Byzyantium transition to Musicoin spec (#7841)

* Add test chain spec for musicoin byzantium testnet

* Add MCIP-6 Byzyantium transition to Musicoin spec

* Update mcip6_byz.json

* ethcore: update musicoin byzantium block number

* ethcore: update musicoin byzantium block number

* ethcore: update musicoin bootnodes

* Update musicoin.json

* Update musicoin.json

* More bootnodes.

ethstore/cli/src/main.rs

@@ -266,7 +266,7 @@ fn execute<S, I>(command: I) -> Result<String, Error> where I: IntoIterator<Item
 		let password = load_password(&args.arg_password)?;
 		let account_ref = open_args_vault_account(&store, address, &args)?;
 		let signature = store.sign(&account_ref, &password, &message)?;
-		Ok(format!("0x{:?}", signature))
+		Ok(format!("0x{}", signature))
 	} else if args.cmd_public {
 		let address = args.arg_address.parse().map_err(|_| ethstore::Error::InvalidAccount)?;
 		let password = load_password(&args.arg_password)?;