22:45:28 Installing execjs (2.5.1) 
22:45:28 Gem::InstallError: execjs requires Ruby version >= 2.0.0.
22:45:28 An error occurred while installing execjs (2.5.1), and Bundler cannot continue.
22:45:28 Make sure that `gem install execjs -v '2.5.1'` succeeds before bundling.
22:45:28 make: *** [build/foreman] Error 5
22:45:28 dpkg-buildpackage: error: debian/rules build gave error exit status 2

I think 1.8 Debian packages need this. Maybe also 1.7.