The docs for /etc/portage/bashrc say, Additional package-specific bashrc files can be created in /etc/portage/env. As I just discovered, this is not really true. You can stick functions in /etc/portage/bashrc, but /etc/portage/env only accepts VARIABLE=VALUE assignments.
Duplicate of bug #388781.
*** This bug has been marked as a duplicate of bug 388781 ***