Adjust the default script to make it work for python3.

src/Products/PythonScripts/PythonScript.py

@@ -67,8 +67,11 @@
     ' of your server in a browser.')
 
 manage_addPythonScriptForm = DTMLFile('www/pyScriptAdd', globals())
-_default_file = os.path.join(package_home(globals()),
-                             'www', 'default_py')
+
+if six.PY3:
+    _default_file = os.path.join(package_home(globals()), 'www', 'default_py3')
+else:
+    _default_file = os.path.join(package_home(globals()), 'www', 'default_py2')
 
 _marker = []  # Create a new marker object
 

src/Products/PythonScripts/www/default_py3

@@ -0,0 +1,13 @@
+# Example code:
+
+# Import a standard function, and get the HTML request and response objects.
+from Products.PythonScripts.standard import html_quote
+request = container.REQUEST
+response =  request.response
+
+# Return a string identifying this script.
+print ("This is the", script.meta_type, '"%s"' % script.getId(), end=' ')
+if script.title:
+    print ("(%s)" % html_quote(script.title), end=' ')
+print ("in", container.absolute_url())
+return printed