def full_changelog_header_branch(branch, ancestor)
      h = ["branch: #{branch} <#{@repo.references["refs/heads/#{branch}"].target_id}>"]
      h << "from ancestor with: #{ancestor} <#{@repo.references["refs/heads/#{ancestor}"].target_id}>" unless ancestor.nil?
      Koios::Doc.write {[pre(h)]}
    end
def full_changelog_header_branch(branch, ancestor)
      h = ["branch: #{branch} <#{@repo.references["refs/heads/#{branch}"].target_id}>"]
      h << "from ancestor with: #{ancestor} <#{@repo.references["refs/heads/#{ancestor}"].target_id}>" unless ancestor.nil?
      Koios::Doc.write {[pre(h)]}
    end
Get the header when a branch is defined
 @param [String] branch Show commits for a branch
 @param [String] ancestor Ancestor or nil
 @return [String] header with a branch