Brandon Williams [off-list ref] writes:

 	if (recurse_submodules &&
-	    (show_stage || show_deleted || show_others || show_unmerged ||
+	    (show_deleted || show_others || show_unmerged ||
 	     show_killed || show_modified || show_resolve_undo ||
-	     show_valid_bit || show_tag || show_eol || with_tree ||
-	     (line_terminator == '\0')))
+	     with_tree))
 		die("ls-files --recurse-submodules unsupported mode");

Ahh, one more thing, and this comment probably applies to 2/4 not
this one, but if the intention is to shrink this "not supported yet"
check as the series progresses, in the earlier step the check would
need to make sure no pathspec is given, which is first supported in
4/4, I think.  It is not a big deal to require rerolling by itself,
bit if you are rerolling 2/4 for other reasons, then...