gitlabhq/app/views/layouts/_search.html.haml

.search
  = form_tag search_path, method: :get, class: 'navbar-form pull-left' do |f|
    = text_field_tag "search", nil, placeholder: "Search", class: "search-input"
    = hidden_field_tag :group_id, @group.try(:id)
    = hidden_field_tag :project_id, @project.try(:id)

:javascript
  $(function(){
    $("#search").autocomplete({
      source: #{raw search_autocomplete_source},
      select: function(event, ui) { location.href = ui.item.url }
    });
  });