Fix merge-request-reopen button title

Closes #4069

app/views/projects/merge_requests/show/_mr_title.html.haml

@@ -17,9 +17,9 @@
   .issue-btn-group.pull-right
     - if can?(current_user, :update_merge_request, @merge_request)
       - if @merge_request.open?
-        = link_to 'Close', merge_request_path(@merge_request, merge_request: { state_event: :close }), method: :put, class: "btn btn-grouped btn-close", title: "Close merge request"
-        = link_to edit_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), class: "btn btn-grouped issuable-edit", id: "edit_merge_request" do
+        = link_to 'Close', merge_request_path(@merge_request, merge_request: { state_event: :close }), method: :put, class: 'btn btn-grouped btn-close', title: 'Close merge request'
+        = link_to edit_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), class: 'btn btn-grouped issuable-edit', id: 'edit_merge_request' do
           %i.fa.fa-pencil-square-o
           Edit
       - if @merge_request.closed?
-        = link_to 'Reopen', merge_request_path(@merge_request, merge_request: {state_event: :reopen }), method: :put, class: "btn btn-grouped btn-reopen reopen-mr-link", title: "Close merge request"
+        = link_to 'Reopen', merge_request_path(@merge_request, merge_request: {state_event: :reopen }), method: :put, class: 'btn btn-grouped btn-reopen reopen-mr-link', title: 'Reopen merge request'