fixes milestone dropdown not select issue

CHANGELOG.md

 Please view this file on the master branch, on stable branches it's out of date.
 
 ## 8.14.0 (2016-11-22)
-
+- Fix Milestone dropdown not stay selected for `Upcoming` and `No Milestone` option !7117
 - Backups do not fail anymore when using tar on annex and custom_hooks only. !5814
 - Adds user project membership expired event to clarify why user was removed (Callum Dryden)
 - Trim leading and trailing whitespace on project_path (Linus Thiel)

app/views/shared/issuable/_milestone_dropdown.html.haml

 - project = @target_project || @project
 - extra_class = extra_class || ''
 - show_menu_above = show_menu_above || false
-- selected_text = selected.try(:title)
+- selected_text = selected.try(:title) || params[:milestone_title]
 - dropdown_title = local_assigns.fetch(:dropdown_title, "Filter by milestone")
 - if selected.present?
-  = hidden_field_tag(name, name == :milestone_title ? selected.title : selected.id)
+  = hidden_field_tag(name, name == :milestone_title ? selected_text : selected.id)
 = dropdown_tag(milestone_dropdown_label(selected_text), options: { title: dropdown_title, toggle_class: "js-milestone-select js-filter-submit #{extra_class}", filter: true, dropdown_class: "dropdown-menu-selectable dropdown-menu-milestone",
   placeholder: "Search milestones", footer_content: project.present?, data: { show_no: true, show_menu_above: show_menu_above, show_any: show_any, show_upcoming: show_upcoming, field_name: name, selected: selected.try(:title), project_id: project.try(:id), milestones: milestones_filter_dropdown_path, default_label: "Milestone" } }) do
   - if project

spec/features/issues/filter_by_milestone_spec.rb

@@ -11,6 +11,7 @@ feature 'Issue filtering by Milestone', feature: true do
     visit_issues(project)
     filter_by_milestone(Milestone::None.title)
 
+    expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: 'No Milestone')
     expect(page).to have_css('.issue', count: 1)
   end
 
@@ -22,6 +23,7 @@ feature 'Issue filtering by Milestone', feature: true do
       visit_issues(project)
       filter_by_milestone(Milestone::Upcoming.title)
 
+      expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: 'Upcoming')
       expect(page).to have_css('.issue', count: 0)
     end
 
@@ -33,6 +35,7 @@ feature 'Issue filtering by Milestone', feature: true do
       visit_issues(project)
       filter_by_milestone(Milestone::Upcoming.title)
 
+      expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: 'Upcoming')
       expect(page).to have_css('.issue', count: 1)
     end
 
@@ -44,6 +47,7 @@ feature 'Issue filtering by Milestone', feature: true do
       visit_issues(project)
       filter_by_milestone(Milestone::Upcoming.title)
 
+      expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: 'Upcoming')
       expect(page).to have_css('.issue', count: 0)
     end
   end
@@ -55,6 +59,7 @@ feature 'Issue filtering by Milestone', feature: true do
     visit_issues(project)
     filter_by_milestone(milestone.title)
 
+    expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: milestone.title)
     expect(page).to have_css('.issue', count: 1)
   end
 
@@ -70,6 +75,7 @@ feature 'Issue filtering by Milestone', feature: true do
       visit_issues(project)
       filter_by_milestone(milestone.title)
 
+      expect(page).to have_css('.milestone-filter .dropdown-toggle-text', text: milestone.title)
       expect(page).to have_css('.issue', count: 1)
     end
   end