The nltk source archive comes in zip format, unzip should be added in its dependencies. On a system without unzip What does not work: 1. emerge nltk # it fails while trying to extract archive Workaround: 1. emerge unzip 2. emerge nltk Reproducible: Always
+ 14 Feb 2012; <pl@gentoo.org> nltk-2.0.1_rc1.ebuild, nltk-2.0_beta9.ebuild: + Adding unzip dep for #402981