Fix BlockTransformer Py3 issues (#21376)

Django's reverse can handle Unicode for arguments.

cms/lib/xblock/runtime.py

@@ -17,7 +17,7 @@ def handler_url(block, handler_name, suffix='', query='', thirdparty=False):
         raise NotImplementedError("edX Studio doesn't support third-party xblock handler urls")
 
     url = reverse('component_handler', kwargs={
-        'usage_key_string': six.text_type(block.scope_ids.usage_id).encode('utf-8'),
+        'usage_key_string': six.text_type(block.scope_ids.usage_id),
         'handler': handler_name,
         'suffix': suffix,
     }).rstrip('/')

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -859,7 +859,7 @@ class MongoModuleStore(ModuleStoreDraftAndPublished, ModuleStoreWriteBase, Mongo
         course_key = self.fill_in_run(course_key)
         parent_cache = self._get_parent_cache(self.get_branch_setting())
 
-        while to_process and depth is None or depth >= 0:
+        while to_process and (depth is None or depth >= 0):
             children = []
             for item in to_process:
                 self._clean_item_data(item)

lms/djangoapps/lms_xblock/runtime.py

@@ -51,7 +51,7 @@ def handler_url(block, handler_name, suffix='', query='', thirdparty=False):
 
     url = reverse(view_name, kwargs={
         'course_id': six.text_type(block.location.course_key),
-        'usage_id': quote_slashes(six.text_type(block.scope_ids.usage_id).encode('utf-8')),
+        'usage_id': quote_slashes(six.text_type(block.scope_ids.usage_id)),
         'handler': handler_name,
         'suffix': suffix,
     })