Merge branch 'gitaly-remove-fetch-ref' into 'master'

Annotate Gitlab::Git::Repository#fetch_ref

See merge request gitlab-org/gitlab-ce!20742

lib/gitlab/git/repository.rb

@@ -826,6 +826,10 @@ module Gitlab
         end
       end
+      # This method, fetch_ref, is used from within
+      # Gitlab::Git::OperationService. OperationService will eventually only
+      # exist in gitaly-ruby. When we delete OperationService from gitlab-ce
+      # we can also remove fetch_ref.
       def fetch_ref(source_repository, source_ref:, target_ref:)
         Gitlab::Git.check_namespace!(source_repository)
         source_repository = RemoteRepository.new(source_repository) unless source_repository.is_a?(RemoteRepository)

lib/gitlab/import_export/merge_request_parser.rb

@@ -25,6 +25,7 @@ module Gitlab
         @project.repository.create_branch(@merge_request.target_branch, @merge_request.target_branch_sha)
       end
+      # Gitaly migration: https://gitlab.com/gitlab-org/gitaly/issues/1295
       def fetch_ref
         @project.repository.fetch_ref(@project.repository, source_ref: @diff_head_sha, target_ref: @merge_request.source_branch)
       end