title: PyQt4: AttributeError: 'QLineEdit' object has no attribute 'setPlaceholderText'
body: <p>I have a QLineEdit, and I want to set a placeholder text. When I call <code>setPlaceholderText(string)</code> I get an AttributeError, but:</p>
  
  <pre><code>&gt;&gt;&gt; from PyQt4 import QtCore
  &gt;&gt;&gt; QtCore.PYQT_VERSION_STR
  '4.7.4'
  &gt;&gt;&gt; QtCore.QT_VERSION_STR
  '4.7.0'
  </code></pre>
  
  <p>and from the QAssistant:</p>
  
  <blockquote>
    <p>This property holds the line edit's
    placeholder text.<br>
    ...<br>
    This property was introduced in Qt 4.7.</p>
  </blockquote>