Work around bug in pprint.pformat. Closes gh-148

IPython/core/displayhook.py

@@ -193,7 +193,11 b' class DisplayHook(Configurable):'
         """
         try:
             if self.shell.pprint:
+                try:
                 result_repr = pformat(result)
+                except:
+                    # Work around possible bugs in pformat
+                    result_repr = repr(result)
                 if '\n' in result_repr:
                     # So that multi-line strings line up with the left column of
                     # the screen, instead of having the output prompt mess up

IPython/core/hooks.py

@@ -163,7 +163,11 b' def result_display(self,arg):'
     """
     
     if self.pprint:
+        try:
         out = pformat(arg)
+        except:
+            # Work around possible bugs in pformat
+            out = repr(arg)
         if '\n' in out:
             # So that multi-line strings line up with the left column of
             # the screen, instead of having the output prompt mess up