New test mode that allows run_parts to fail silently if the directory
is not found. Patch from Bastian Blank
diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index be09ea6..f33dbc4 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -1010,7 +1010,7 @@
 
 	buf = xmalloc(xstrlen(opt) + 19);
 	sprintf(buf, "/etc/network/if-%s.d", opt);
-	run_parts(&buf, 0);
+	run_parts(&buf, 2);
 	free(buf);
 	return (1);
 }