Admin/build_release

--- a/Admin/build_release	Sun May 16 19:37:15 2021 +0200
+++ b/Admin/build_release	Mon May 17 13:57:19 2021 +1000
@@ -2,6 +2,7 @@
 #
 # DESCRIPTION: build full Isabelle distribution from repository
 
+unset CDPATH
 THIS="$(cd "$(dirname "$0")"; pwd)"
 
 "$THIS/build" jars || exit $?