title: Hamburger icon doesn't animate with AppCompat library
body: <p>I'm using the appcompat-v7 library to backport the Lollipop Toolbar. It looks correct, but it does not animate when I click the hamburger icon (it stays a hamburger icon). What's strange is that if I open the drawer and rotate the device, the hamburger icon changes to an arrow like it should had already been prior to rotating. If I rotate back to portrait, it stays an arrow. Here's my code:</p>
  
  <pre><code>import android.support.v7.app.ActionBarDrawerToggle;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_base_navigation);
  
      mDrawerLayout = ButterKnife.findById(this, R.id.drawer_layout);
      mContentFrameLayout = ButterKnife.findById(this, R.id.content);
  
      mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.open_menu, R.string.close_menu);
      mDrawerLayout.setDrawerListener(this);
  }
  
  @Override
  protected void onPostCreate(Bundle savedInstanceState) {
      super.onPostCreate(savedInstanceState);
      mDrawerToggle.syncState();
  }
  
  @Override
  public void onConfigurationChanged(Configuration newConfig) {
      super.onConfigurationChanged(newConfig);
      mDrawerToggle.onConfigurationChanged(newConfig);
  }
  
  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
      return mDrawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
  }
  </code></pre>
  
  <p>And my theme:</p>
  
  <pre><code>&lt;resources&gt;
  
      &lt;style name="AppTheme" parent="Theme.AppCompat.Light" /&gt;
  
  &lt;/resources&gt;
  </code></pre>