reviewing the code on github it seems these two lines were removed:
ln -s /usr/local/lib/z-push/z-push-admin.php /usr/sbin/z-push-admin
ln -s /usr/local/lib/z-push/z-push-top.php /usr/sbin/z-push-top
Adding that back manually fixes z-push-admin for me
Wondering if it does for you?
See for yourself: