Makefile:2019: recipe for target 'src/cython/vapoursynth.c' failed
make: *** [src/cython/vapoursynth.c] Error 1
recipe for target 'src/cython/vapoursynth.c' failed
Probably due to Cython version 0.25.2 (Debian stretch default) source(old) source(new)
sudo -H pip3 install --upgrade pip
sudo -H pip3 install --upgrade cython
recipe for target 'vspipe' failed
make: *** [vspipe] Error 1