The keyword "source" is a bashism. To fix, apply the following patch, or set the first line of /etc/X11/chooser.sh to #!/bin/bash 10,11c10,11 < [ -f /etc/conf.d/basic ] && source /etc/conf.d/basic < [ -f /etc/rc.conf ] && source /etc/rc.conf --- > [ -f /etc/conf.d/basic ] && . /etc/conf.d/basic > [ -f /etc/rc.conf ] && . /etc/rc.conf
thanks bjorn, changed in portage for 4.3.0 and up.