Run emerge =x11-libs/qt-4.1.3 and results : * Qt-4 is incompatible with the 'nodoc' feature of portage. Please disable this feature and retry While I consider this very trivial, it still shouldn't be there, emerge should just skip the nodoc feature and a warning that the nodoc cannot be used and continue with the emerge.
I think since I've fixed the mkspecs location in the 4.1.2 ebuild that this probably isn't even needed anymore.
I've removed the check from qt-4.1.3 as it's not needed anymore, but note that making the ebuild fail instead of just pose a warning was necessary because qt would be rendered useless without the mkspec files that were originally installed in the doc directory.