This is related to Bug 29217 and the test case "Serialization-text-11":

  <test><![CDATA[
    declare option Q{http://www.w3.org/2010/xslt-xquery-serialization}method "text";
    "a&#xD;aa&#xD;&#xA;a&#xD;&#xA;"]]></test>
  <result>
    <serialization-matches><![CDATA[^a\raa\r?\na\r?\n$]]></serialization-matches>
  </result>

To cover different system environments, the test results could be rewritten to:

  <result>
    <any-of>
      <serialization-matches>^a\raa\r\na\r\n$</serialization-matches>
      <serialization-matches>^a\raa\r\r\na\r\r\n$</serialization-matches>
      <serialization-matches>^a\raa\r\ra\r\r$</serialization-matches>
    </any-of>
  </result>