main: Assume / for ls if no path given

Since it just is kind of a sane default.

tests/test-basic.sh

@@ -19,7 +19,7 @@
 
 set -e
 
-echo "1..34"
+echo "1..35"
 
 . $(dirname $0)/libtest.sh
 
@@ -241,3 +241,7 @@ $OSTREE checkout test2 test2-checkout
 (cd test2-checkout && $OSTREE commit --link-checkout-speedup -b test2 -s "tmp")
 echo "ok commit with link speedup"
 
+cd ${test_tmpdir}
+$OSTREE ls test2
+echo "ok ls with no argument"
+