dev-util/nvidia-cuda-toolkit-5.5.22 did not emerge on my system, as I had /var/tmp/portage because I did not have enough space on that partition. The problem was solved as soon as I remounted it with more space. Without the check it makes emerge crash. As it is has quite huge distfiles (829,510 kB) an early check could help many users.
+ 17 Sep 2013; Justin Lecher <jlec@gentoo.org> + nvidia-cuda-toolkit-5.5.22.ebuild: + Check for disk space, #483690 +