rosa-build/app/views/projects/pull_requests/_nav_tabs.html.haml

%ul.nav.nav-tabs#pull_tabs
  %li
    %a{"data-toggle" => "tab", :href => "#discussion"}=t 'pull_requests.tabs.discussion'
  -if @stats
    %li
      %a{"data-toggle" => "tab", :href => "#diff"}="#{t'pull_requests.tabs.diff'} (#{@stats.count})"
  -if @commits
    %li
      - commits_message = @commits.count.to_s
      - commits_message << '+' if @total_commits > @commits.count
      %a{"data-toggle" => "tab", :href => "#commits"}="#{t'pull_requests.tabs.commits'} (#{commits_message})"

:javascript
  $(document).ready(function() {
    var tab = 'discussion';
    if(document.location.href.match(/(.*)#diff(.*)/)) {
      tab = 'diff';
    } else if(document.location.href.match(/(.*)#commits(.*)/)) {
      tab = 'commits';
    };
    $('#pull_tabs a[href="#'+tab+'"]').tab('show');
  });