Try to strengthen test_httpservers (issue #11617)
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
index a16e0e3..39ebc26 100644
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -38,8 +38,8 @@
         self.test_object = test_object
 
     def run(self):
-        self.server = HTTPServer(('', 0), self.request_handler)
-        self.test_object.PORT = self.server.socket.getsockname()[1]
+        self.server = HTTPServer(('localhost', 0), self.request_handler)
+        self.test_object.HOST, self.test_object.PORT = self.server.socket.getsockname()
         self.test_object.server_started.set()
         self.test_object = None
         try:
@@ -66,7 +66,7 @@
         support.threading_cleanup(*self._threads)
 
     def request(self, uri, method='GET', body=None, headers={}):
-        self.connection = http.client.HTTPConnection('localhost', self.PORT)
+        self.connection = http.client.HTTPConnection(self.HOST, self.PORT)
         self.connection.request(method, uri, body, headers)
         return self.connection.getresponse()
 
@@ -107,7 +107,7 @@
 
     def setUp(self):
         BaseTestCase.setUp(self)
-        self.con = http.client.HTTPConnection('localhost', self.PORT)
+        self.con = http.client.HTTPConnection(self.HOST, self.PORT)
         self.con.connect()
 
     def test_command(self):