io: fix corner case in EPIPE handling.

If io_read is always called, we don't know that it will actually read,
so it might not notice error.  In that case, safest to fail immediately.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/io.c

@@ -399,8 +399,7 @@ void io_ready(struct io_conn *conn, int pollflags)
 		/* If we're writing to a closed pipe, we need to wait for
 		 * read to fail if we're duplex: we want to drain it! */
 		do_plan(conn, &conn->plan[IO_OUT],
-			(conn->plan[IO_IN].status == IO_POLLING
-			 || conn->plan[IO_IN].status == IO_ALWAYS));
+			conn->plan[IO_IN].status == IO_POLLING);
 }
 
 void io_do_always(struct io_conn *conn)