Travis fails on changes about the Website #2252
Description
Travis builds are failing due to some error on "Bundler".
Warning: the lockfile is being updated to Bundler 2, after which you will be unable to return to Bundler 1.
Bundle complete! 3 Gemfile dependencies, 29 gems now installed.
Bundled gems are installed into `./vendor/bundle`
rm -rf _site local-generated generated_site
JEKYLL_ENV=production bundle exec jekyll build \
--config _config.yml,_config.apache.yml
Bundler::LockfileError: You must use Bundler 2 or greater with this lockfile.
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/lockfile_parser.rb:108:in `warn_for_outdated_bundler_version'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/lockfile_parser.rb:95:in `initialize'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/definition.rb:72:in `new'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/definition.rb:72:in `initialize'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/dsl.rb:200:in `new'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/dsl.rb:200:in `to_definition'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/dsl.rb:12:in `evaluate'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/definition.rb:33:in `build'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler.rb:129:in `definition'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler.rb:95:in `setup'
/usr/local/lib/ruby/gems/2.4.0/gems/bundler-1.15.4/lib/bundler/setup.rb:19:in `<top (required)>'
/usr/local/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/local/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
bundler: failed to load command: jekyll (/home/travis/build/apache/bookkeeper/site/vendor/bundle/ruby/2.4.0/bin/jekyll)
make: *** [apache] Error 1
Makefile:24: recipe for target 'apache' failed