Per https://www.mail-archive.com/bug-tar@gnu.org/msg05440.html

diff --git a/tests/difflink.at b/tests/difflink.at

index eadfb08..4e01176 100644

--- a/tests/difflink.at

+++ b/tests/difflink.at

@@ -21,7 +21,7 @@ mkdir a

 genfile -f a/x

 ln -s x a/y

 ln a/y a/z

-tar cf a.tar a

+tar cf a.tar a/x a/y a/z

 rm a/z

 ln -s x a/z

 tar df a.tar