bpo-32662: Try making test_asyncio.test_server more reliable (#5338)

Lib/test/test_asyncio/test_server.py

 import asyncio
 import socket
+import time
 import threading
 import unittest
 
+from test import support
 from test.test_asyncio import utils as test_utils
 from test.test_asyncio import functional as func_tests
 
@@ -16,6 +18,14 @@ class BaseStartServer(func_tests.FunctionalTestCaseMixin):
         HELLO_MSG = b'1' * 1024 * 5 + b'\n'
 
         def client(sock, addr):
+            for i in range(10):
+                time.sleep(0.2)
+                if srv.is_serving():
+                    break
+            else:
+                raise RuntimeError
+
+            sock.settimeout(2)
             sock.connect(addr)
             sock.send(HELLO_MSG)
             sock.recv_all(1)
@@ -33,7 +43,7 @@ class BaseStartServer(func_tests.FunctionalTestCaseMixin):
                 await srv.serve_forever()
 
         srv = self.loop.run_until_complete(asyncio.start_server(
-            serve, '127.0.0.1', 0, loop=self.loop, start_serving=False))
+            serve, support.HOSTv4, 0, loop=self.loop, start_serving=False))
 
         self.assertFalse(srv.is_serving())
 
@@ -65,6 +75,7 @@ class SelectorStartServerTests(BaseStartServer, unittest.TestCase):
         started = threading.Event()
 
         def client(sock, addr):
+            sock.settimeout(2)
             started.wait(5)
             sock.connect(addr)
             sock.send(HELLO_MSG)