Fix threads test

src/lab.rs

@@ -113,7 +113,7 @@ pub fn test_mutants(
         for build_dir in build_dirs {
             threads.push(scope.spawn(|| {
                 let build_dir = build_dir; // move it into this thread
-                trace!("start thread in {build_dir:?}");
+                trace!(thread_id = ?thread::current().id(), ?build_dir, "start thread");
                 loop {
                     // Not a while loop so that it only holds the lock briefly.
                     let next = numbered_mutants.lock().expect("lock mutants queue").next();

tests/jobs.rs

@@ -30,7 +30,7 @@ fn jobs_option_accepted_and_causes_multiple_threads() {
     // This might be brittle, as the ThreadId debug form is not specified, and
     // also _possibly_ everything will complete on one thread before the next
     // gets going, though that seems unlikely.
-    let re = Regex::new(r#"\{thread=ThreadId\(\d+\)\}"#).expect("compile regex");
+    let re = Regex::new(r#"start thread thread_id=ThreadId\(\d+\)"#).expect("compile regex");
     let matches = re
         .find_iter(&debug_log)
         .map(|m| m.as_str())