Fixed typo in displaypub

Regression introduced in  #4229

IPython/core/displaypub.py

@@ -126,7 +126,7 b' class CapturingDisplayPublisher(DisplayPublisher):'
     
     def clear_output(self, wait=False):
         super(CapturingDisplayPublisher, self).clear_output(wait)
-        if other:
+        
             # empty the list, *do not* reassign a new list
             del self.outputs[:]