lib.sh: fix regression

i was being a bit too clever about some optimisations

revert this change. otherwise, nothing will download
or build

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/lib.sh

@@ -223,7 +223,8 @@ e()
 singletree()
 {
 	for targetfile in "config/${1}/"*/target.cfg; do
-		[ -e "$targetfile" ] && [ -f "$targetfile" ] && return 1
+		[ -e "$targetfile" ] || continue
+		[ -f "$targetfile" ] && return 1
 	done
 }