Add test for timeout=0

Author: giampaolo

Lib/test/test_subprocess.py

@@ -1417,6 +1417,8 @@ def test_wait(self):
     def test_wait_timeout(self):
         p = subprocess.Popen([sys.executable,
                               "-c", "import time; time.sleep(0.3)"])
+        with self.assertRaises(subprocess.TimeoutExpired) as c:
+            p.wait(timeout=0)
         with self.assertRaises(subprocess.TimeoutExpired) as c:
             p.wait(timeout=0.0001)
         self.assertIn("0.0001", str(c.exception))  # For coverage of __str__.