Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/no_rt.rs

@@ -0,0 +1,41 @@
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
+
+use tokio::net::TcpStream;
+use tokio::sync::oneshot;
+use tokio::time::{timeout, Duration};
+
+use futures::executor::block_on;
+
+use std::net::TcpListener;
+
+#[test]
+#[should_panic(
+    expected = "there is no reactor running, must be called from the context of a Tokio 1.x runtime"
+)]
+fn timeout_panics_when_no_tokio_context() {
+    block_on(timeout_value());
+}
+
+#[test]
+#[should_panic(
+    expected = "there is no reactor running, must be called from the context of a Tokio 1.x runtime"
+)]
+fn panics_when_no_reactor() {
+    let srv = TcpListener::bind("127.0.0.1:0").unwrap();
+    let addr = srv.local_addr().unwrap();
+    block_on(TcpStream::connect(&addr)).unwrap();
+}
+
+async fn timeout_value() {
+    let (_tx, rx) = oneshot::channel::<()>();
+    let dur = Duration::from_millis(10);
+    let _ = timeout(dur, rx).await;
+}
+
+#[test]
+#[should_panic(
+    expected = "there is no reactor running, must be called from the context of a Tokio 1.x runtime"
+)]
+fn io_panics_when_no_tokio_context() {
+    let _ = tokio::net::TcpListener::from_std(std::net::TcpListener::bind("127.0.0.1:0").unwrap());
+}