Don't backport changes to nav_btns.

app/views/projects/issues/_nav_btns.html.haml

-- show_rss_button = local_assigns.fetch(:show_rss_button, true)
-- show_export_button = local_assigns.fetch(:show_export_button, true)
-
-- if show_rss_button
-  = link_to params.merge(rss_url_options), class: 'btn btn-default append-right-10 has-tooltip', title: 'Subscribe' do
-    = icon('rss')
-
-- if show_export_button
-  = render 'projects/issues/export_issues/button'
-
+= link_to params.merge(rss_url_options), class: 'btn btn-default append-right-10 has-tooltip', title: 'Subscribe' do
+  = icon('rss')
 - if @can_bulk_update
   = button_tag "Edit issues", class: "btn btn-default append-right-10 js-bulk-update-toggle"
-
 = link_to "New issue", new_project_issue_path(@project,
                                               issue: { assignee_id: issues_finder.assignee.try(:id),
                                                        milestone_id: issues_finder.milestones.first.try(:id) }),