chore: checkpoint before Python removal

vendor/tokio/tests/io_repeat.rs

@@ -0,0 +1,18 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(miri)))]
+
+use tokio::io::AsyncReadExt;
+
+#[tokio::test]
+async fn repeat_poll_read_is_cooperative() {
+    tokio::select! {
+        biased;
+        _ = async {
+            loop {
+                let mut buf = [0u8; 4096];
+                tokio::io::repeat(0b101).read_exact(&mut buf).await.unwrap();
+            }
+        } => {},
+        _ = tokio::task::yield_now() => {}
+    }
+}