fix(in_mem): fix the clone logic (paritytech#14038)

client/api/src/in_mem.rs

@@ -114,6 +114,7 @@ struct BlockchainStorage<Block: BlockT> {
 }
 
 /// In-memory blockchain. Supports concurrent reads.
+#[derive(Clone)]
 pub struct Blockchain<Block: BlockT> {
 	storage: Arc<RwLock<BlockchainStorage<Block>>>,
 }
@@ -124,13 +125,6 @@ impl<Block: BlockT> Default for Blockchain<Block> {
 	}
 }
 
-impl<Block: BlockT + Clone> Clone for Blockchain<Block> {
-	fn clone(&self) -> Self {
-		let storage = Arc::new(RwLock::new(self.storage.read().clone()));
-		Blockchain { storage }
-	}
-}
-
 impl<Block: BlockT> Blockchain<Block> {
 	/// Get header hash of given block.
 	pub fn id(&self, id: BlockId<Block>) -> Option<Block::Hash> {