gollum-lib dependency mismatch between upstream and Gemfile.lock
gollum-lib (4.0.3)
github-markup (~> 1.3.3)
gollum-grit_adapter (~> 1.0)
nokogiri (~> 1.6.4)
rouge (~> 1.10.1)
sanitize (~> 2.1.0)
stringex (~> 2.5.1)
but if you look at https://rubygems.org/gems/gollum-lib/versions/4.0.3 it lists rouge with ~> 1.7.4