Fix ref_switcher path

app/views/shared/_ref_switcher.html.haml

 = form_tag switch_project_refs_path(@project), method: :get, class: "project-refs-form" do
   = select_tag "ref", grouped_options_refs, class: "project-refs-select chosen"
   = hidden_field_tag :destination, destination
-  - if respond_to?(:path)
+  - if defined?(path)
     = hidden_field_tag :path, path

app/views/tree/_head.html.haml

 %ul.nav.nav-tabs
   %li
-    = render partial: 'shared/ref_switcher', locals: {destination: 'tree', path: params[:path]}
+    = render partial: 'shared/ref_switcher', locals: {destination: 'tree', path: @path}
   %li{class: "#{'active' if (controller.controller_name == "tree") }"}
     = link_to project_tree_path(@project, @ref) do
       Source

app/views/tree/show.js.haml

@@ -2,7 +2,7 @@
   // Load Files list
   $("#tree-holder").html("#{escape_javascript(render(partial: "tree", locals: {repo: @repo, commit: @commit, tree: @tree}))}");
   $("#tree-content-holder").show("slide", { direction: "right" }, 150);
-  $('.project-refs-form #path').val("#{params[:path]}");
+  $('.project-refs-form #path').val("#{@path}");
 
   //  Load last commit log for each file in tree
   $('#tree-slider').waitForImages(function() {