mplayer-1.0_pre6 should be named mplayer-1.0_pre6a, as the file it downloads has changed and the current version of MPlayer is 1.0_pre6a. Reproducible: Always Steps to Reproduce:
a single letter after a suffix number is not supported -> http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=1#doc_chap2
Sorry, didn't know that. Perhaps that should be changed. So it would be a minor portage bug. (Not really important, it's just that I wondered why it is downloading a new file, when I allready had an up to date version downloaded a few days ago. So the consistency of distfiles and emerged packages was broken, which I needed because I wanted to install exactly the same system on a different machine, without downloading the whole distfiles again.)
