This is a tracker bug for all packages depending on Qt build tools apart from qmake itself. For example: lrelease, moc, rcc, uic. Depending on the version of Qt installed on the user's system, these may be found in different directories. For this reason we have added qt4_get_bindir and qt5_get_bindir helper functions in qmake-utils.eclass.
Packages not providing the right path to these tools should block this tracker, and be fixed by using the helper functions. As qmake-utils does not export any default ebuild phases, it does not interfere with the build system in the ebuilds inheriting it.