Fixing bugs and adding comment

IPython/testing/globalipapp.py

@@ -136,7 +136,7 b' def start_ipython():'
     config = tools.default_config()
 
     # Create and initialize our test-friendly IPython instance.
-    shell = iplib.InteractiveShell(
+    shell = iplib.InteractiveShell.instance(
         config=config, 
         user_ns=ipnsdict(), user_global_ns={}
     )

IPython/utils/traitlets.py

@@ -401,6 +401,8 b' class HasTraits(object):'
 
     def __init__(self, **kw):
         # Allow trait values to be set using keyword arguments.
+        # We need to use setattr for this to trigger validation and
+        # notifications.
         for key, value in kw.iteritems():
             setattr(self, key, value)