message: Explicitly specify the locale when converting to upper case.
  The result of this should not depend on what locale the user has set on their machine.
diff: @@ -31,6 +31,7 @@ import java.io.Reader;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.charset.Charset;
  +import java.util.Locale;
  import java.util.concurrent.Executor;
  import java.util.concurrent.Executors;
  import java.util.regex.Matcher;
  @@ -266,7 +267,7 @@ public class KeysDownloader {
  private static void validate(String url) {
  try {
  URL tmp = new URL(url);
  - if (!tmp.getProtocol().toLowerCase().equals("https")) {
  + if (!tmp.getProtocol().toLowerCase(Locale.US).equals("https")) {
  throw new IllegalArgumentException("url must point to a HTTPS server");
  }
  } catch (MalformedURLException ex) {
  