chore: checkpoint before Python removal

vendor/async-stream/tests/spans_preserved.rs

@@ -0,0 +1,15 @@
+use async_stream::stream;
+use futures_util::pin_mut;
+use futures_util::stream::StreamExt;
+
+#[tokio::test]
+async fn spans_preserved() {
+    let s = stream! {
+     assert_eq!(line!(), 8);
+    };
+    pin_mut!(s);
+
+    while s.next().await.is_some() {
+        unreachable!();
+    }
+}