Extract epic nav into separate partial for easier CE => EE

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

 - type = local_assigns.fetch(:type, :issues)
 - page_context_word = type.to_s.humanize(capitalize: false)
-- issuables = @issues || @merge_requests || @epics
 
 %ul.nav-links.issues-state-filters
-  - if type != :epics
-    %li{ class: active_when(params[:state] == 'opened') }>
-      = link_to page_filter_path(state: 'opened', label: true), id: 'state-opened', title: "Filter by #{page_context_word} that are currently opened.", data: { state: 'opened' } do
-        #{issuables_state_counter_text(type, :opened)}
+  %li{ class: active_when(params[:state] == 'opened') }>
+    = link_to page_filter_path(state: 'opened', label: true), id: 'state-opened', title: "Filter by #{page_context_word} that are currently opened.", data: { state: 'opened' } do
+      #{issuables_state_counter_text(type, :opened)}
 
-    - if type == :merge_requests
-      %li{ class: active_when(params[:state] == 'merged') }>
-        = link_to page_filter_path(state: 'merged', label: true), id: 'state-merged', title: 'Filter by merge requests that are currently merged.', data: { state: 'merged' } do
-          #{issuables_state_counter_text(type, :merged)}
+  - if type == :merge_requests
+    %li{ class: active_when(params[:state] == 'merged') }>
+      = link_to page_filter_path(state: 'merged', label: true), id: 'state-merged', title: 'Filter by merge requests that are currently merged.', data: { state: 'merged' } do
+        #{issuables_state_counter_text(type, :merged)}
 
-      %li{ class: active_when(params[:state] == 'closed') }>
-        = link_to page_filter_path(state: 'closed', label: true), id: 'state-closed', title: 'Filter by merge requests that are currently closed and unmerged.', data: { state: 'closed' } do
-          #{issuables_state_counter_text(type, :closed)}
-    - else
-      %li{ class: active_when(params[:state] == 'closed') }>
-        = link_to page_filter_path(state: 'closed', label: true), id: 'state-closed', title: 'Filter by issues that are currently closed.', data: { state: 'closed' } do
-          #{issuables_state_counter_text(type, :closed)}
+    %li{ class: active_when(params[:state] == 'closed') }>
+      = link_to page_filter_path(state: 'closed', label: true), id: 'state-closed', title: 'Filter by merge requests that are currently closed and unmerged.', data: { state: 'closed' } do
+        #{issuables_state_counter_text(type, :closed)}
+  - else
+    %li{ class: active_when(params[:state] == 'closed') }>
+      = link_to page_filter_path(state: 'closed', label: true), id: 'state-closed', title: 'Filter by issues that are currently closed.', data: { state: 'closed' } do
+        #{issuables_state_counter_text(type, :closed)}
 
-  %li{ class: active_when(params[:state] == 'all') }>
-    = link_to page_filter_path(state: 'all', label: true), id: 'state-all', title: "Show all #{page_context_word}.", data: { state: 'all' } do
-      #{issuables_state_counter_text(type, :all)}
+  = render 'shared/issuable/nav_links/all', page_context_word: page_context_word, counter: issuables_state_counter_text(type, :all)

app/views/shared/issuable/nav_links/_all.html.haml

+- page_context_word = local_assigns.fetch(:page_context_word)
+- counter = local_assigns.fetch(:counter)
+
+%li{ class: active_when(params[:state] == 'all') }>
+  = link_to page_filter_path(state: 'all', label: true), id: 'state-all', title: "Show all #{page_context_word}.", data: { state: 'all' } do
+    #{counter}

ee/app/views/shared/_epics.html.haml

 .top-area
-  = render 'shared/issuable/nav', type: :epics
+  = render 'shared/issuable/epic_nav', type: :epics
   .nav-controls
     - if can?(current_user, :create_epic, @group)
       - content_for :page_specific_javascripts do

ee/app/views/shared/issuable/_epic_nav.html.haml

+- type = local_assigns.fetch(:type, :epics)
+- page_context_word = type.to_s.humanize(capitalize: false)
+
+%ul.nav-links.issues-state-filters
+  = render 'shared/issuable/nav_links/all', page_context_word: page_context_word, counter: issuables_state_counter_text(type, :all)
+