WITH_BASH or WITH_KSH do not work if they are not installed.
(See PR ports/54915 for fench/aster - same problem)
Fix: Please apply the following patch:
How-To-Repeat: On a machine where bash is not installed, try to install astk-serveur
with the knob WITH_BASH=yes => it will try to fetch the port
shells/bash, which does not exist. Idem for ksh.