MuseScore git master fails to compile with -DUSE_SYSTEM_QTSINGLEAPPLICATION=ON

Everytime I compile MuseScore from git with -DUSE_SYSTEM_QTSINGLEAPPLICATION=ON, I get the following error:


$ cmake -DUSE_SYSTEM_QTSINGLEAPPLICATION=ON .
-- The C compiler identification is GNU 4.9.2
-- The CXX compiler identification is GNU 4.9.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Doxygen: /usr/bin/doxygen (found version "1.8.9.1")
found Doxygen
-- configured /home/kalle/Sources/MuseScore/build/Doxyfile.in --> /home/kalle/Sources/MuseScore/Doxyfile
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.28")
-- checking for module 'libpulse'
-- package 'libpulse' not found
-- Found lame: /usr/lib64/libmp3lame.so
Alsa found.
Pulseaudio not found.
-- jack (jack audio connection kit) >= 0.98.0 found
portaudio detected /usr/include /usr/lib64 -lportaudio -lm -lpthread
-- precompiled header generation
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
QTSINGLEAPPLICATION_INCLUDE_DIRS
used as include directory in directory /home/kalle/Sources/MuseScore/mscore

-- Configuring incomplete, errors occurred!
See also "/home/kalle/Sources/MuseScore/CMakeFiles/CMakeOutput.log".

I am running Gentoo GNU/Linux unstable on amd64. This patch fixes the issue:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0ffff26..47307c4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -326,7 +326,7 @@ endif(APPLE)
##

if (USE_SYSTEM_QTSINGLEAPPLICATION)
- find_path(QTSINGLEAPPLICATION_INCLUDE_DIRS qtsingleapplication.h PATH_SUFFIXES QtSolutions)
+ find_path(QTSINGLEAPPLICATION_INCLUDE_DIRS qtsingleapplication.h PATH_SUFFIXES qt5/QtSolutions)
find_library(QTSINGLEAPPLICATION_LIBRARIES QtSolutions_SingleApplication-2.6)
else(USE_SYSTEM_QTSINGLEAPPLICATION)
subdirs (thirdparty/singleapp)

Please tell me if you need more information.

Thanks in advance,
Karl