chore: checkpoint before Python removal

vendor/parking/tests/loom.rs

@@ -0,0 +1,28 @@
+#![cfg(loom)]
+
+#[test]
+fn smoke() {
+    loom::model(|| {
+        let (p, u) = parking::pair();
+
+        loom::thread::spawn(move || {
+            p.park();
+        });
+
+        u.unpark();
+    });
+}
+
+#[test]
+fn yield_then_unpark() {
+    loom::model(|| {
+        let (p, u) = parking::pair();
+
+        loom::thread::spawn(move || {
+            loom::thread::yield_now();
+            u.unpark();
+        });
+
+        p.park();
+    });
+}