title: AnimationSet defined via XML does not repeat
body: <p>I have this xml code, that should simulate a sort of "heart beat" animation. Image that use it should scale twice, and return to original size, then restart again:</p>
  
  <pre><code>&lt;set xmlns:android="http://schemas.android.com/apk/res/android"
  android:repeatCount="-1"
  android:repeatMode="restart"
  android:shareInterpolator="true" &gt;
  
  &lt;scale
      android:duration="500"
      android:fromXScale="1"
      android:fromYScale="1"
      android:pivotX="50%"
      android:pivotY="50%"
      android:toXScale="1.2"
      android:toYScale="1.2" /&gt;
  &lt;scale
      android:duration="500"
      android:fromXScale="1.2"
      android:fromYScale="1.2"
      android:pivotX="50%"
      android:pivotY="50%"
      android:toXScale="1.4"
      android:toYScale="1.4" /&gt;
  &lt;scale
      android:duration="500"
      android:fromXScale="1.4"
      android:fromYScale="1.4"
      android:pivotX="50%"
      android:pivotY="50%"
      android:toXScale="1.0"
      android:toYScale="1.0" /&gt;
  
  &lt;/set&gt;
  </code></pre>
  
  <p>and this is how i add this animation set to my imageview:</p>
  
  <pre><code>AnimationSet heart_pulse = new AnimationSet(true);
              heart_pulse.addAnimation(AnimationUtils.loadAnimation(activity,
                      R.anim.pulsexml));
  
              logo.setAnimation(heart_pulse);
              logo.startAnimation(heart_pulse);
  </code></pre>
  
  <p>but animation is executed only one time, then it stops. Why?</p>