extmod/modlwip: Unconditionally return POLLHUP when polling new socket.

POSIX poll should always return POLLERR and POLLHUP in revents, regardless
of whether they were requested in the input events flags.

See issues #4290 and #5172.

extmod/modlwip.c

@@ -1468,7 +1468,7 @@ STATIC mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
 
         if (socket->state == STATE_NEW) {
             // New sockets are not connected so set HUP
-            ret |= flags & MP_STREAM_POLL_HUP;
+            ret |= MP_STREAM_POLL_HUP;
         } else if (socket->state == STATE_PEER_CLOSED) {
             // Peer-closed socket is both readable and writable: read will
             // return EOF, write - error. Without this poll will hang on a

tests/net_hosted/connect_poll.py

@@ -12,9 +12,8 @@ def test(peer_addr):
     poller.register(s)
 
     # test poll before connect
-    # note: CPython can return POLLHUP, so use the IN|OUT mask
     p = poller.poll(0)
-    print(len(p), p[0][-1] & (select.POLLIN | select.POLLOUT))
+    print(len(p), p[0][-1])
 
     s.connect(peer_addr)
 

tests/net_hosted/connect_poll.py.exp

@@ -1,3 +1,3 @@
-1 4
+1 20
 1
 1 4