Display project icon from default branch

This commit makes sure that the project icon is
being read from the default branch instead of
'master'

CHANGELOG

@@ -17,6 +17,7 @@ v 8.11.1 (unreleased)
   - Does not halt the GitHub import process when an error occurs
   - Fix file links on project page when default view is Files !5933
   - Change using size to use count and caching it for number of group members
+  - Use the default branch for displaying the project icon instead of master !5792 (Hannes Rosenögger)
 
 v 8.11.0
   - Use test coverage value from the latest successful pipeline in badge. !5862

app/controllers/projects/avatars_controller.rb

@@ -4,7 +4,7 @@ class Projects::AvatarsController < Projects::ApplicationController
   before_action :authorize_admin_project!, only: [:destroy]
 
   def show
-    @blob = @repository.blob_at_branch('master', @project.avatar_in_git)
+    @blob = @repository.blob_at_branch(@repository.root_ref, @project.avatar_in_git)
     if @blob
       headers['X-Content-Type-Options'] = 'nosniff'
 

app/models/project.rb

@@ -1035,6 +1035,7 @@ class Project < ActiveRecord::Base
                                         "refs/heads/#{branch}",
                                         force: true)
     repository.copy_gitattributes(branch)
+    repository.expire_avatar_cache(branch)
     reload_default_branch
   end
 

app/models/repository.rb

@@ -1065,7 +1065,7 @@ class Repository
 
     @avatar ||= cache.fetch(:avatar) do
       AVATAR_FILES.find do |file|
-        blob_at_branch('master', file)
+        blob_at_branch(root_ref, file)
       end
     end
   end

spec/models/project_spec.rb

@@ -1442,4 +1442,35 @@ describe Project, models: true do
       expect(shared_project.authorized_for_user?(master, Gitlab::Access::MASTER)).to be(true)
     end
   end
+
+  describe 'change_head' do
+    let(:project) { create(:project) }
+
+    it 'calls the before_change_head method' do
+      expect(project.repository).to receive(:before_change_head)
+      project.change_head(project.default_branch)
+    end
+
+    it 'creates the new reference with rugged' do
+      expect(project.repository.rugged.references).to receive(:create).with('HEAD',
+                                                                            "refs/heads/#{project.default_branch}",
+                                                                            force: true)
+      project.change_head(project.default_branch)
+    end
+
+    it 'copies the gitattributes' do
+      expect(project.repository).to receive(:copy_gitattributes).with(project.default_branch)
+      project.change_head(project.default_branch)
+    end
+
+    it 'expires the avatar cache' do
+      expect(project.repository).to receive(:expire_avatar_cache).with(project.default_branch)
+      project.change_head(project.default_branch)
+    end
+
+    it 'reloads the default branch' do
+      expect(project).to receive(:reload_default_branch)
+      project.change_head(project.default_branch)
+    end
+  end
 end