In the document it mentioned coreutils8 which doesn't supported by bootstrap-prefix.sh
# ./bootstrap-prefix.sh $EPREFIX/tmp coreutils8
* Bootstrapping Gentoo prefixed portage installation using
* host: i686-pc-linux-gnu
* prefix: /opt/gentoo/tmp
!!! bootstrap target coreutils8 unknown
not the GDP's concern; belongs to the prefix team, as it's in their /proj/ space.
yegle, does coreutils work for you?
*** This bug has been marked as a duplicate of bug 415439 ***