Merge 1.5.5.3 in

builtin-commit.c

@@ -223,6 +223,8 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
 
 	if (interactive) {
 		interactive_add(argc, argv, prefix);
+		if (read_cache() < 0)
+			die("index file corrupt");
 		commit_style = COMMIT_AS_IS;
 		return get_index_file();
 	}