Drop the tokio runtime before the task_manager (#6548)

* Initial commit

Forked at: ece0364170
Parent branch: origin/master

* Drop the tokio runtime before the task_manager

The tokio runtime must be dropped before the task_manager. Otherwise the objects the task_manager
keep alive are dropped before the tasks are finished.

substrate/client/cli/src/runner.rs

@@ -236,7 +236,7 @@ impl<C: SubstrateCli> Runner<C> {
 		self.tokio_runtime.block_on(main(task_manager.future().fuse()))
 			.map_err(|e| e.to_string())?;
 		task_manager.terminate();
-		drop(task_manager);
+		drop(self.tokio_runtime);
 		Ok(())
 	}