Can't import input formats using XML

If an input format i.e. "PHP code" has no element import will fail.

<?xml version="1.0"?>
<drupal>
  <input-formats>
    <input-format>
      <format>1</format>
      <format-name>Filtered HTML</format-name>
      <roles>
        <role>1</role>
        <role>2</role>
        <role>3</role>
        <role>4</role>
      </roles>
      <cache>1</cache>
    </input-format>
    <input-format>
      <format>2</format>
      <format-name>PHP code</format-name>
      <cache>0</cache>
    </input-format>
    <input-format>
      <format>3</format>
      <format-name>Full HTML</format-name>
      <roles>
        <role>3</role>
      </roles>
      <cache>1</cache>
    </input-format>
  </input-formats>
</drupal>