Fix.

diff --git a/testing/scripts/lib/copy_dirtrees_of_tags b/testing/scripts/lib/copy_dirtrees_of_tags
new file mode 120000 (symlink)
index 0000000..d33a150
--- /dev/null
+++ b/testing/scripts/lib/copy_dirtrees_of_tags
@@ -0,0 +1 @@
+../../../bookworm/scripts/lib/copy_dirtrees_of_tags
\ No newline at end of file