Doesn't work with jekyll 2.5.2

[mulle-nat]

Building a simple jekyll site (I tried two templates) with the plugin fails:

root@51859d8d85df:/var/jekyll/feeling-responsive# jekyll build -d /var/www/jekyll/feeling-responsive
Configuration file: /var/jekyll/feeling-responsive/_config.yml
            Source: /var/jekyll/feeling-responsive
       Destination: /var/www/jekyll/feeling-responsive
      Generating... 
jekyll 2.5.2 | Error:  undefined method `deep_merge' for #<Hash:0x0000000120c460>

But after removing the plugin all is well:

root@51859d8d85df:/var/jekyll/feeling-responsive# rm _plugins/static_comments.rb 
root@51859d8d85df:/var/jekyll/feeling-responsive# jekyll build -d /var/www/jekyll/feeling-responsive
Configuration file: /var/jekyll/feeling-responsive/_config.yml
            Source: /var/jekyll/feeling-responsive
       Destination: /var/www/jekyll/feeling-responsive
      Generating... 
                    done.
 Auto-regeneration: disabled. Use --watch to enable.``