The archive is no longer available under the current SRC_URI
Annoying upstream moved the archives from http://download.qt-project.org/official_releases/qt/ to http://download.qt-project.org/archive/qt/... for no apparent reason.
Fixed in cvs and git. I also changed qt5-build.eclass to the use new location, except for alpha/beta/rc tarballs that are still in development_releases only.