This package had the same issue as described in issue #15744. The custom
installPhase doesn't call pre- and post-install hooks like it should.
The solution is also similar (see commit a1facf3).
Commit 0055c6a introduced a new preConfigure hook that sets the right
qmake path. Unfortunately the mkDerivation attributes of twmn override
the whole configurePhase, so this hook isn't run at all.
This fixes the build of twmn and it now successfully compiles on my
machine.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>