turns out miri just hates localset

tokio/src/task/local.rs

@@ -921,3 +921,22 @@ impl task::Schedule for Arc<Shared> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn local_current_thread_scheduler() {
+        let f = async {
+            LocalSet::new()
+                .run_until(async {
+                    spawn_local(async {}).await.unwrap();
+                })
+                .await;
+        };
+        crate::runtime::Builder::new_current_thread()
+            .build()
+            .expect("rt")
+            .block_on(f)
+    }
+}