OpenBlock::new take IntoIterator instead of mutable ref to Iterator (#10480)

ethcore/src/client/test_client.rs

@@ -416,7 +416,7 @@ impl PrepareOpenBlock for TestBlockChainClient {
 			gas_range_target,
 			extra_data,
 			false,
-			&mut Vec::new().into_iter(),
+			None,
 		)?;
 		// TODO [todr] Override timestamp for predictability
 		open_block.set_timestamp(*self.latest_block_timestamp.read());