Failing python tests seen in e.g. here are fixed (could not fix the nasty java.io.IOException: Cannot run program "/opt/pyenv/shims/python3": error=2, No such file or directory error in travis+docker env...)
Travis build now fails if python tests fail.
Moreover cache is used for SBT, so the test suite is twice faster.
This PR fixes several points:
java.io.IOException: Cannot run program "/opt/pyenv/shims/python3": error=2, No such file or directoryerror in travis+docker env...)Moreover cache is used for SBT, so the test suite is twice faster.