Fixed a missing variable initialisation deep in the Query bowels.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9081 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/sql/query.py

@@ -808,6 +808,7 @@ class Query(object):
         self.where.relabel_aliases(change_map)
         for pos, col in enumerate(self.select):
             if isinstance(col, (list, tuple)):
+                old_alias = col[0]
                 self.select[pos] = (change_map.get(old_alias, old_alias), col[1])
             else:
                 col.relabel_aliases(change_map)

tests/regressiontests/queries/models.py

@@ -966,6 +966,11 @@ about them and shouldn't do bad things.
 >>> expected == result
 True
 
+Make sure bump_prefix() (an internal Query method) doesn't (re-)break.
+>>> query = Tag.objects.values_list('id').order_by().query
+>>> query.bump_prefix()
+>>> print query.as_sql()[0]
+SELECT U0."id" FROM "queries_tag" U0
 """}
 
 # In Python 2.3 and the Python 2.6 beta releases, exceptions raised in __len__