mod_http_oauth2: Reject duplicate form-urlencoded parameters Per RFC 6749 section 3.1 > Request and response parameters MUST NOT be included more than once. Thanks to OAuch for pointing out Also cleans up some of the icky behavior of formdecode(), like returning a string if no '=' is included.

<tr>
  <th>What is {x} {op} {y}?</th><td>
    <input name="captcha_challenge" type="hidden" value="{challenge}">
    <input name="captcha_reply" pattern="[0-9]+" required type="number">
  </td></tr>