Bug#880159: qtchooser: Make plain "qmake" invocation fail

[Antonio]

edit /usr/lib/x86_64-linux-gnu/qtchooser//default.conf and add this line
solve the problem:

+/usr/lib/qt5/bin/
/usr/lib/x86_64-linux-gnu/qt5/bin
/usr/lib/x86_64-linux-gnu