config_service: Fixed bug regarding None entries in latest_revisions dict.

appengine/config_service/api.py

 # Copyright 2015 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import logging
 
 from google.appengine.api import memcache
 from google.appengine.ext import ndb
 from protorpc import messages
 from protorpc import message_types
@@ skipping 123 matching lines @@
     return self.GetMappingResponseMessage(
         mappings=[
           self.GetMappingResponseMessage.Mapping(
               config_set=cs.key.id(), location=cs.location)
           for cs in config_sets
           if can_read[cs.key.id()]
         ]
     )
 
   ##############################################################################
-  # endpoint: get_config_set
+  # endpoint: get_config_sets
 
   class GetConfigSetsResponseMessage(messages.Message):
     config_sets = messages.MessageField(ConfigSet, 1, repeated=True)
 
   @auth.endpoints_method(
     endpoints.ResourceContainer(
         message_types.VoidMessage,
         config_set=messages.StringField(1),
         include_last_import_attempt=messages.BooleanField(2),
         include_files=messages.BooleanField(3),
     ),
     GetConfigSetsResponseMessage,
     http_method='GET',
     path='config-sets')
   @auth.public # ACL check inside
   def get_config_sets(self, request):
     """Returns config sets."""
     if request.config_set and not can_read_config_set(request.config_set):
       raise endpoints.ForbiddenException()
 
     # The files property must always be a list of File objects (not None).
     files = []
     if request.include_files:
       if not request.config_set:
         raise endpoints.BadRequestException(
             'Must specify config_set to use include_files')
       latest_revisions = storage.get_latest_revisions_async(
           [request.config_set]).get_result()
-      file_keys = storage.get_file_keys(
-          request.config_set, latest_revisions[request.config_set])
-      files = [File(path=key.id()) for key in file_keys]
+      if latest_revisions[request.config_set]:
+        file_keys = storage.get_file_keys(
+            request.config_set, latest_revisions[request.config_set])
+        files = [File(path=key.id()) for key in file_keys]
 
     config_sets = storage.get_config_sets_async(
         config_set=request.config_set).get_result()
 
     if request.include_last_import_attempt:
       attempts = ndb.get_multi([
         storage.last_import_attempt_key(cs.key.id()) for cs in config_sets
       ])
     else:
       attempts = [None] * len(config_sets)
@@ skipping 326 matching lines @@
 
 def can_read_config_sets(config_sets):
   try:
     return acl.can_read_config_sets(config_sets)
   except ValueError as ex:
     raise endpoints.BadRequestException(ex.message)
 
 
 def can_read_config_set(config_set):
   return can_read_config_sets([config_set]).get(config_set)