Fix ApplicationHelper#changelog_url with frozen strings

    return AppConfig.settings.changelog_url.get if AppConfig.settings.changelog_url.present?

    url = "https://github.com/diaspora/diaspora/blob/master/Changelog.md"

    url.sub!('/master/', "/#{AppConfig.git_revision}/") if AppConfig.git_revision.present?

    url

    return url if AppConfig.git_revision.blank?

    url.sub("/master/", "/#{AppConfig.git_revision}/")

  end

  def source_url