use rollbacked version of grit to make gollum works

Gemfile

@@ -23,7 +23,7 @@ gem 'omniauth-github'
 # Extracting information from a git repository
 # Since gollum requires grit we cannot use gitlab-grit gem name any more. Use grit instead
-gem "grit", '~> 2.5.0', git: 'https://github.com/gitlabhq/grit.git', ref: 'c15e2758ec75f99230cd0fbcc9110bf932c0bf05'
+gem "grit", '~> 2.5.0', git: 'https://github.com/gitlabhq/grit.git', ref: '42297cdcee16284d2e4eff23d41377f52fc28b9d'
 gem 'grit_ext', '~> 0.8.1'
 # Ruby/Rack Git Smart-HTTP Server Handler

Gemfile.lock

@@ -8,8 +8,8 @@ GIT
 GIT
   remote: https://github.com/gitlabhq/grit.git
-  revision: c15e2758ec75f99230cd0fbcc9110bf932c0bf05
-  ref: c15e2758ec75f99230cd0fbcc9110bf932c0bf05
+  revision: 42297cdcee16284d2e4eff23d41377f52fc28b9d
+  ref: 42297cdcee16284d2e4eff23d41377f52fc28b9d
   specs:
     grit (2.5.0)
       diff-lcs (~> 1.1)