catalyst: allow GENTOO_MIRRORS to be passed in through the environment
catalyst: allow GENTOO_MIRRORS to be passed in through the environment

coreos/scripts,glevand/coreos--scripts,smilart/scripts,marineam/coreos-scripts,coreos/scripts,glevand/coreos--scripts,smilart/scripts,marineam/coreos-scripts,marineam/coreos-scripts,smilart/scripts