Don't override issue page description in project layout.

app/helpers/page_layout_helper.rb

@@ -27,11 +27,9 @@ module PageLayoutHelper
   #
   # Returns an HTML-safe String.
   def page_description(description = nil)
-    @page_description ||= brand_title
-
     if description.present?
       @page_description = description.squish
-    else
+    elsif @page_description.present?
       sanitize(@page_description, tags: []).truncate_words(30)
     end
   end
@@ -41,11 +39,8 @@ module PageLayoutHelper
 
     subject = @project || @user || @group
 
-    if subject.present?
-      subject.avatar_url || default
-    else
-      default
-    end
+    image = subject.avatar_url if subject.present?
+    image || default
   end
 
   # Define or get attributes to be used as Twitter card metadata

app/views/layouts/_head.html.haml

+- page_description brand_title unless page_description
+
 - site_name = "GitLab"
 %head{prefix: "og: http://ogp.me/ns#"}
   %meta{charset: "utf-8"}

app/views/layouts/group.html.haml

 - page_title       @group.name
-- page_description @group.description
+- page_description @group.description  unless page_description
 - header_title     group_title(@group) unless header_title
 - sidebar          "group"             unless sidebar
 

app/views/layouts/project.html.haml

 - page_title       @project.name_with_namespace
-- page_description @project.description
+- page_description @project.description    unless page_description
 - header_title     project_title(@project) unless header_title
 - sidebar          "project"               unless sidebar
 

spec/helpers/page_layout_helper_spec.rb

@@ -2,10 +2,8 @@ require 'rails_helper'
 
 describe PageLayoutHelper do
   describe 'page_description' do
-    it 'defaults to value returned by brand_title helper' do
-      allow(helper).to receive(:brand_title).and_return('Foo')
-
-      expect(helper.page_description).to eq 'Foo'
+    it 'defaults to nil' do
+      expect(helper.page_description).to eq nil
     end
 
     it 'returns the last-pushed description' do