After doing some research in the issue queue, it appears that this is really a problem with the Aptitude problem resolver and multi-arch.
apt-get install sees the gettext:i386 dependency as a "recommends" and doesn't install it.
See https://bugs.launchpad.net/ubuntu/+source/aptitude/+bug/975898
and
https://bugs.launchpad.net/ubuntu/+source/aptitude/+bug/831768
After doing some research in the issue queue, it appears that this is really a problem with the Aptitude problem resolver and multi-arch.
apt-get install sees the gettext:i386 dependency as a "recommends" and doesn't install it.
See https:/ /bugs.launchpad .net/ubuntu/ +source/ aptitude/ +bug/975898
and
https:/ /bugs.launchpad .net/ubuntu/ +source/ aptitude/ +bug/831768