'qhelpgenerator: Command not found' during qt5.git integration in '5.10'

cd corelib/ && ( test -e Makefile || /home/qt/work/build/qtbase/bin/qmake -o Makefile /home/qt/work/qt/qt5/qtbase/src/corelib/corelib.pro ) && make -f Makefile qch_docs
make[4]: Entering directory '/home/qt/work/build/qtbase/src/corelib'
/home/qt/work/build/qtbase/bin/qhelpgenerator /home/qt/work/build/qtbase/doc/qtcore/qtcore.qhp -o /home/qt/work/build/qtbase/doc/qtcore.qch
make[4]: /home/qt/work/build/qtbase/bin/qhelpgenerator: Command not found
Makefile:1688: recipe for target 'qch_docs' failed
make[4]: *** [qch_docs] Error 127
make[4]: Leaving directory '/home/qt/work/build/qtbase/src/corelib'
Makefile:1338: recipe for target 'sub-corelib-qch_docs' failed
make[3]: *** [sub-corelib-qch_docs] Error 2
make[3]: Leaving directory '/home/qt/work/build/qtbase/src'
Makefile:423: recipe for target 'sub-src-qch_docs' failed
make[2]: *** [sub-src-qch_docs] Error 2
make[2]: Leaving directory '/home/qt/work/build/qtbase'
Makefile:1999: recipe for target 'module-qtbase-qch_docs' failed
make[1]: *** [module-qtbase-qch_docs] Error 2
make[1]: Leaving directory '/home/qt/work/build'
Makefile:1246: recipe for target 'docs' failed
make: *** [docs] Error 2