Pushed with these additional tweaks:
diff --git a/lib/userspec.c b/lib/userspec.c
index 760b007..e115552 100644
--- a/lib/userspec.c
+++ b/lib/userspec.c
@@ -114,7 +114,7 @@ parse_with_separator (char const *spec, char const *separato
char const *g;
char *gname = NULL;
uid_t unum = *uid;
* lib/userspec.c (parse_user_spec): If the GID param is NULL,
then avoid group processing and treat the full spec as a user.
(parse_with_separator): Allow the USERNAME and GROUPNAME to
be optional params (NULL), in which case they're ignored.
* tests/test-userspec.c (main): Ensure NULL params are i
