roken_detach_prep() close pipe

lib/roken/detach.c

@@ -129,6 +129,8 @@ roken_detach_prep(int argc, char **argv, char *special_arg)
     do {
         bytes = read(pipefds[0], buf, sizeof(buf));
     } while (bytes == -1 && errno == EINTR);
+    (void) close(pipefds[0]);
+    pipefds[0] = -1;
     if (bytes == -1) {
         /*
          * No need to wait for the process.  We've killed it.  If it