Fix listing commit branch/tags that contain special characters

changelogs/unreleased/dm-refs-contains-sha-encoding.yml

+---
+title: Fix listing commit branch/tags that contain special characters
+merge_request:
+author:
+type: fixed

lib/gitlab/git/repository.rb

@@ -8,6 +8,7 @@ module Gitlab
     class Repository
       include Gitlab::Git::RepositoryMirroring
       include Gitlab::Git::Popen
+      include Gitlab::EncodingHelper
 
       ALLOWED_OBJECT_DIRECTORIES_VARIABLES = %w[
         GIT_OBJECT_DIRECTORY
@@ -1479,7 +1480,7 @@ module Gitlab
         names.lines.each do |line|
           next unless line.start_with?(refs_prefix)
 
-          refs << line.rstrip[left_slice_count..-1]
+          refs << encode_utf8(line.rstrip[left_slice_count..-1])
         end
 
         refs

spec/lib/gitlab/git/repository_spec.rb

@@ -604,17 +604,20 @@ describe Gitlab::Git::Repository, seed_helper: true do
     shared_examples 'returning the right branches' do
       let(:head_id) { repository.rugged.head.target.oid }
       let(:new_branch) { head_id }
+      let(:utf8_branch) { 'branch-é' }
 
       before do
         repository.create_branch(new_branch, 'master')
+        repository.create_branch(utf8_branch, 'master')
       end
 
       after do
         repository.delete_branch(new_branch)
+        repository.delete_branch(utf8_branch)
       end
 
       it 'displays that branch' do
-        expect(repository.branch_names_contains_sha(head_id)).to include('master', new_branch)
+        expect(repository.branch_names_contains_sha(head_id)).to include('master', new_branch, utf8_branch)
       end
     end