title: Exception from QTextEdit textChanged signal
body: <p>I'm using Python3 and PyQt5 to create an application containing form elements such as <code>QLineEdit</code> and <code>QTextEdit</code>. </p>
  
  <p>I collect data from a <code>QLineEdit</code> as follows (this is working properly):</p>
  
  <pre><code>    self.rolAdi = QtWidgets.QLineEdit(self.centralWidget)
      self.rolAdi.setObjectName("rolAdi")
  
      self.rolAdi.textChanged.connect(self.textSonDurum)
  
  def textSonDurum(self, s):
      print("Text changed...&gt;&gt;&gt; "+s)
  </code></pre>
  
  <p>However, the same method using a <code>QTextEdit</code> control doesn't work - the program stops whenever I change the content of the control:</p>
  
  <pre><code>   self.IP = QtWidgets.QTextEdit(self.centralWidget)
     self.IP.setObjectName("IP")
  
     self.IP.textChanged.connect(self.textSonDurum)
  
  def textSonDurum(self, s):
      print("Text changed...&gt;&gt;&gt; "+s)
  </code></pre>
  
  <p>I researched about this problem and I found a suggestion involving using the disconnect function, but  cannot find it in PyQt5.</p>
  
  <pre><code>self.IP.textChanged.disconnect()
  </code></pre>
  
  <p><strong>Output Error</strong>:</p>
  
  <pre><code>TypeError: disconnect() failed between 'textChanged' and all its connections
  </code></pre>
  
  <p>(The full code is very long to paste it here but let me know if you need any other part).</p>