When making a grp package set, 'grp-chroot.sh' script is run TWO times (because "grp.sh run" is run two times (for srcset and for pkgset)). So, it needs the 'envscript' file in /tmp for setting the environment variables. If the file is deleted at the first time, the second time there is no personal environment. Solutions: 1. Not to remove the file (I personally did that change in my catalyst source) 2. Set the environment variable (and maintain it) at catalyst python code (when grp.sh is called).
fixed in CVS