title: ant delete task gives error
body: <p>I want delete a directory only if exists.</p>
  
  <pre><code> &lt;target name="clean"&gt;
          &lt;delete dir="${COMP_BUILD}" /&gt;
      &lt;/target&gt;
  </code></pre>
  
  <p>this gets error</p>
  
  <pre><code>clean:
     [delete] Deleting directory U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\ENT_APP\ESW\bgc-esw-services\build
  
  BUILD FAILED
  U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\BUILD\ESW\ESWBUILD\build.xml:451: The following error occurred while executing this line:
  U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\ENT_APP\ESW\bgc-esw-web\build.xml:207: The following error occurred while executing this line:
  U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\ENT_APP\ESW\bgc-esw-web\build.xml:84: The following error occurred while executing this line:
  U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\ENT_APP\ESW\bgc-esw-services\build.xml:64: Unable to delete directory U:\id824275_03_2011_06_JUN_ESW\CCS_WSC_ECM\ecm_esw\app\ENT_APP\ESW\bgc-esw-services\build\lib
  </code></pre>