This seems to be a reoccurence of bug 141412 in version 0.16.1. When "test" is enabled in FEATURES in /etc/make.conf, emerging gettext-0.16.1 fails during running tests in the section lang-gawk:
< 2 morceaux de gateau
> 2 pieces of cake
So which gawk version you have installed?
you're right, it works with the latest gawk...