Avoid race conditions in binding sockets in tests

Author: msimacek

graalpython/lib-python/3/test/support/__init__.py

@@ -783,10 +783,9 @@ def bind_port(sock, host=HOST):
         if hasattr(socket, 'SO_EXCLUSIVEADDRUSE'):
             sock.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)
 
-    # XXX GraalVM change: bind to a specific port
-    # Our bind with port 0 doesn't know the real port until listen() is called
-    # sock.bind((host, 0))
-    sock.bind((host, 8756))
+    sock.bind((host, 0))
+    # XXX GraalVM change: our bind with port 0 doesn't know the real port until listen() is called
+    sock.listen()
     port = sock.getsockname()[1]
     return port