also test panic from thread with name

tests/run-pass/concurrency/simple.rs

@@ -59,6 +59,15 @@ fn panic() {
     assert_eq!(*msg, "Hello!");
 }
 
+fn panic_named() {
+    thread::Builder::new().name("childthread".to_string()).spawn(move || {
+        panic!("Hello, world!");
+    })
+    .unwrap()
+    .join()
+    .unwrap_err();
+}
+
 fn main() {
     create_and_detach();
     create_and_join();
@@ -69,4 +78,5 @@ fn main() {
     create_move_in();
     create_move_out();
     panic();
+    panic_named();
 }

tests/run-pass/concurrency/simple.stderr

@@ -1,3 +1,4 @@
 warning: thread support is experimental. For example, Miri does not detect data races yet.
 
 thread '<unnamed>' panicked at 'Hello!', $DIR/simple.rs:54:9
+thread 'childthread' panicked at 'Hello, world!', $DIR/simple.rs:64:9