core: add ^ for rev-parse

tests/t0000-basic.sh

@@ -20,7 +20,7 @@
 
 set -e
 
-echo "1..7"
+echo "1..8"
 
 . libtest.sh
 
@@ -35,6 +35,11 @@ echo "ok check"
 ostree checkout $ot_repo test2 checkout-test2
 echo "ok checkout"
 
+ostree rev-parse $ot_repo test2
+ostree rev-parse $ot_repo 'test2^'
+ostree rev-parse $ot_repo 'test2^^' 2>/dev/null && (echo 1>&2 "rev-parse test2^^ unexpectedly succeeded!"; exit 1)
+echo "ok rev-parse"
+
 cd checkout-test2
 assert_has_file firstfile
 assert_has_file baz/cow