Fix serialization of extrinsics. (#1402)

substrate/node/primitives/src/lib.rs

@@ -31,8 +31,6 @@ extern crate sr_primitives as runtime_primitives;
 extern crate substrate_primitives as primitives;
 
 use runtime_primitives::generic;
-#[cfg(feature = "std")]
-use primitives::bytes;
 use runtime_primitives::{OpaqueExtrinsic, traits::BlakeTwo256};
 
 pub use runtime_primitives::BasicInherentData as InherentData;