Don't try to export orphaned draft items.

#278

cms/djangoapps/contentstore/tests/test_contentstore.py

@@ -386,6 +386,10 @@ class ContentStoreToyCourseTest(ModuleStoreTestCase):
 
         draft_store.clone_item(vertical.location, vertical.location)
 
+        # We had a bug where orphaned draft nodes caused export to fail. This is here to cover that case.
+        draft_store.clone_item(vertical.location, Location(['i4x', 'edX', 'full',
+                                                             'vertical', 'no_references', 'draft']))
+
         for child in vertical.get_children():
             draft_store.clone_item(child.location, child.location)
 

common/lib/xmodule/xmodule/modulestore/xml_exporter.py

@@ -50,12 +50,14 @@ def export_to_xml(modulestore, contentstore, course_location, root_dir, course_d
             draft_course_dir = export_fs.makeopendir('drafts')
             for draft_vertical in draft_verticals:
                 parent_locs = draft_modulestore.get_parent_locations(draft_vertical.location, course.location.course_id)
-                logging.debug('parent_locs = {0}'.format(parent_locs))
-                draft_vertical.xml_attributes['parent_sequential_url'] = Location(parent_locs[0]).url()
-                sequential = modulestore.get_item(Location(parent_locs[0]))
-                index = sequential.children.index(draft_vertical.location.url())
-                draft_vertical.xml_attributes['index_in_children_list'] = str(index)
-                draft_vertical.export_to_xml(draft_course_dir)
+                # Don't try to export orphaned items.
+                if len(parent_locs) > 0:
+                    logging.debug('parent_locs = {0}'.format(parent_locs))
+                    draft_vertical.xml_attributes['parent_sequential_url'] = Location(parent_locs[0]).url()
+                    sequential = modulestore.get_item(Location(parent_locs[0]))
+                    index = sequential.children.index(draft_vertical.location.url())
+                    draft_vertical.xml_attributes['index_in_children_list'] = str(index)
+                    draft_vertical.export_to_xml(draft_course_dir)
 
 
 def export_extra_content(export_fs, modulestore, course_location, category_type, dirname, file_suffix=''):