subprocess.Popen.__exit__ doesn't wait for process end

Lib/test/test_subprocess.py

 import unittest
 from test import support
 import subprocess
 import sys
 import signal
 import io
 import os
 import errno
 import tempfile
 import time
@@ skipping 1572 matching lines @@
                               stderr=subprocess.PIPE) as proc:
             self.assertEqual(proc.stdout.read(), b"stdout")
             self.assertStderrEqual(proc.stderr.read(), b"stderr")
 
         self.assertTrue(proc.stdout.closed)
         self.assertTrue(proc.stderr.closed)
 
     def test_returncode(self):
         with subprocess.Popen([sys.executable, "-c",
                                "import sys; sys.exit(100)"]) as proc:
-            proc.wait()
+            pass
+        # __exit__ calls wait(), so the returncode should be set
         self.assertEqual(proc.returncode, 100)
 
     def test_communicate_stdin(self):
         with subprocess.Popen([sys.executable, "-c",
                               "import sys;"
                               "sys.exit(sys.stdin.read() == 'context')"],
                              stdin=subprocess.PIPE) as proc:
             proc.communicate(b"context")
             self.assertEqual(proc.returncode, 1)
 
@@ skipping 17 matching lines @@
                   ProcessTestCaseNoPoll,
                   HelperFunctionTests,
                   CommandsWithSpaces,
                   ContextManagerTests)
 
     support.run_unittest(*unit_tests)
     support.reap_children()
 
 if __name__ == "__main__":
     unittest.main()