When buliding Qt 5.8.0 from source with an RPM spec file,
the resulting qmake is broken.
Running it in the installed system yields

QMake version 3.1
Using Qt version 5.8.0 in

and it is unable to find any files in system directories, like in /usr/lib64/qt5/mkspecs.

I believe that commit 169a40d511165f6c3c9a71cd5c079786c22d2aca broke it as the appended qt.conf gets removed after stripping the binary, but I have yet to bisect and debug further to confirm. The last successful build was Dec 3, the first broken one Dec 22, so the time frame fits.