Fix runtime error where dict is modified during iteration.

common/lib/xmodule/xmodule/course_module.py

@@ -1153,7 +1153,7 @@ class CourseDescriptor(CourseFields, SequenceDescriptor, LicenseMixin):
 
         # bleh, have to parse the XML here to just pull out the url_name attribute
         # I don't think it's stored anywhere in the instance.
-        course_file = BytesIO(xml_data.encode('ascii', 'ignore'))
+        course_file = BytesIO(six.binary_type(xml_data))
         xml_obj = etree.parse(course_file, parser=edx_xml_parser).getroot()
 
         policy_dir = None

common/lib/xmodule/xmodule/tests/xml/factories.py

@@ -110,7 +110,7 @@ class XmlImportFactory(Factory):
         if inline_xml:
             kwargs['xml_node'].set('not_a_pointer', 'true')
 
-        for key in kwargs.keys():
+        for key in list(kwargs.keys()):
             if key not in XML_IMPORT_ARGS:
                 kwargs['xml_node'].set(key, kwargs.pop(key))