http://bugs.gentoo.org/283725
https://alioth.debian.org/tracker/index.php?func=detail&aid=311740&group_id=30580&atid=411480

--- shadow-4.1.4.2/libmisc/env.c
+++ shadow-4.1.4.2/libmisc/env.c
@@ -251,7 +251,7 @@
 			if (strncmp (*cur, *bad, strlen (*bad)) != 0) {
 				continue;
 			}
-			if (strchr (*cur, '/') != NULL) {
+			if (strchr (*cur, '/') == NULL) {
 				continue;	/* OK */
 			}
 			for (move = cur; NULL != *move; move++) {