get retcode directly

Author: tiran

Lib/test/libregrtest/runtest_mp.py

@@ -235,8 +235,7 @@ def _run_process(self, test_name: str, tmp_dir: str, stdout_fh: TextIO) -> int:
 
             try:
                 # gh-94026: stdout+stderr are written to tempfile
-                popen.wait(timeout=self.timeout)
-                retcode = popen.returncode
+                retcode = popen.wait(timeout=self.timeout)
                 assert retcode is not None
                 return retcode
             except subprocess.TimeoutExpired: