Steps to reproduce:

1. Define host macro {$M01}: 

   <foo></bar>

1. Create HTTP agent item:
   Request type: POST
   Request body type: XML data
   Request body: 

   <data><macro>{$M01}</macro><![CDATA[{$M01}<foo></bar>]]></data>

1. Execute item check

Result:

<data><macro>&amp;lt;foo&amp;gt;&amp;lt;/bar&amp;gt;</macro><![CDATA[<foo></bar><foo></bar>]]></data>

Expected:

<data><macro>&lt;foo&gt;&lt;/bar&gt;</macro><![CDATA[<foo></bar><foo></bar>]]></data>