Package: qtchooser
Version: 63-g13a3d08-1
Severity: important
User: helmutg@debian.org
Usertags: rebootstrap
$ sudo apt-get install qt5-qmake
...
$ qmake -qtconf foo
qmake: could not find a Qt installation of 'conf'
$
That's wrong. qtchooser needs to pass -qtconf down to the actual qmake
rather than interpreting it itself.