tst_qmlcachegen fails to compile

$ cd tests/auto/qml/qmlcachegen
$ gmake
qmlcachegen_wrapper.sh --resource=/home/tjmaciei/src/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen/trickypaths.qrc --resource=/home/tjmaciei/src/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen/trickypaths_umlaut.qrc --resource=/home/tjmaciei/obj/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen/.rcc/qmake_workerscripts_test.qrc --resource=/home/tjmaciei/obj/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen/.rcc/qmake_qmake_immediate.qrc -o .qmlcache/umlaut_qml.cpp /home/tjmaciei/src/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen/umlaut.qml
g++ -c -pipe -pipe -march=native -mno-f16c -mno-rdrnd -g -Wall -W -D_REENTRANT -fPIC -DQT_QML_DEBUG -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_TESTLIB_LIB -DQT_CORE_LIB -DQT_TESTCASE_BUILDDIR='"/home/tjmaciei/obj/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen"' -I/home/tjmaciei/src/qt/qt5/qtdeclarative/tests/auto/qml/qmlcachegen -I. -I/home/tjmaciei/obj/qt/qt5/qtbase/include -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtGui -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtQml/5.12.0 -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtQml/5.12.0/QtQml -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtCore/5.12.0 -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtCore/5.12.0/QtCore -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtQml -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtNetwork -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtTest -I/home/tjmaciei/obj/qt/qt5/qtbase/include/QtCore -I.moc -isystem /usr/include/libdrm -I/home/tjmaciei/src/qt/qt5/qtbase/mkspecs/linux-g++-optimised -o .obj/umlaut_qml.o .qmlcache/umlaut_qml.cpp
.qmlcache/umlaut_qml.cpp:3:14: error: stray ‘\303’ in program
 namespace __B��h_qml {
              ^
.qmlcache/umlaut_qml.cpp:3:15: error: stray ‘\244’ in program
 namespace __B��h_qml {
               ^
.qmlcache/umlaut_qml.cpp:3:16: error: expected ‘{’ before ‘h_qml’
 namespace __Bäh_qml {
                ^~~~~
.qmlcache/umlaut_qml.cpp:3:16: error: ‘h_qml’ does not name a type