Log specific connect failure type (via poll error).

src/common/slurm_protocol_socket_implementation.c

@@ -589,9 +589,12 @@ extern int _slurm_connect (int __fd, struct sockaddr const * __addr,
 		poll_rc = poll(&ufds, 1, 5000);
 		if (poll_rc == 1) {
 			/* poll successfully completed */
-			if (ufds.revents & POLLERR)
-				debug2("connect failure");
-			else
+			if (ufds.revents & POLLERR) {
+				int err = 0, size;
+				getsockopt(__fd, SOL_SOCKET, SO_ERROR, &err, &size);
+				slurm_seterrno(err);
+				debug2("connect failure: %m");
+			} else
 				rc = 0;
 		} else {
 			slurm_seterrno(ETIMEDOUT);