title: ant-contrib - if/then/else task
body: <p>I am using ant, and I have a problem with if/then/else task, (ant-contrib-1.0b3.jar).
  I am running something that can be simplified with build.xml below.<br></p>
  
  <p>I am expecting to obtain from 'ant -Dgiv=Luke' the message</p>
  
  <pre><code>input name: Luke
  should be overwritten with John except for Mark: John
  </code></pre>
  
  <p>but it seems property "giv" is not overwritten inside if/then/else..</p>
  
  <pre><code>input name: Luke
  should be overwritten with John except for Mark: Luke
  </code></pre>
  
  <p>Is it depending from the fact I am using equals task with <code>${giv}</code> ?
  Otherwise what is wrong in my code? </p>
  
  <p>build.xml CODE:</p>
  
  <pre><code>&lt;project name="Friend" default="ifthen" basedir="."&gt;
  
  &lt;property name="runningLocation" location="" /&gt;
  &lt;taskdef resource="net/sf/antcontrib/antcontrib.properties"&gt;
      &lt;classpath&gt;
          &lt;pathelement location="${runningLocation}/antlib/ant-contrib-1.0b3.jar" /&gt;
      &lt;/classpath&gt;
  &lt;/taskdef&gt;
  
  &lt;target name="ifthen"&gt;
  &lt;echo message="input name: ${giv}" /&gt;
  &lt;if&gt;
      &lt;equals arg1="${giv}" arg2="Mark" /&gt;
      &lt;then&gt;
      &lt;/then&gt;
      &lt;else&gt;
          &lt;property name="giv" value="John" /&gt;
      &lt;/else&gt;
  &lt;/if&gt;
  &lt;echo message="should be overwritten with John except for Mark: ${giv}" /&gt;
  &lt;/target&gt;
  &lt;/project&gt;
  </code></pre>