merge backout

diff --cc lib/sqlalchemy/orm/__init__.py
Simple merge

diff --cc test/orm/inheritance/test_polymorph.py
Simple merge

diff --cc test/orm/test_assorted_eager.py
Simple merge

diff --cc test/orm/test_backref_mutations.py
Simple merge

diff --cc test/orm/test_cascade.py
Simple merge

diff --cc test/orm/test_expire.py
Simple merge

diff --cc test/orm/test_mapper.py
Simple merge

diff --cc test/orm/test_merge.py
index fbdbcfe2143974a76a18c1d315dd658e2efd5fb5,15c52a1e01c831e8e13fe4b19e364c42d6b35036..8effd6665d8d0d371a48aba4e8136c7824c43478
--- 1/test/orm/test_merge.py
--- 2/test/orm/test_merge.py
+++ b/test/orm/test_merge.py
@@@ -2,17 -2,16 +2,16 @@@ from test.lib.testing import assert_rai
  import sqlalchemy as sa
  from sqlalchemy import Integer, PickleType, String
  import operator
 -from sqlalchemy.test import testing
 +from test.lib import testing
  from sqlalchemy.util import OrderedSet
- from sqlalchemy.orm import mapper, relationship, create_session, \
-     PropComparator, synonym, comparable_property, sessionmaker, \
-     attributes, Session
+ from sqlalchemy.orm import mapper, relationship, create_session, PropComparator, \
+                             synonym, comparable_property, sessionmaker, attributes
  from sqlalchemy.orm.collections import attribute_mapped_collection
  from sqlalchemy.orm.interfaces import MapperOption
 -from sqlalchemy.test.testing import eq_, ne_
 +from test.lib.testing import eq_, ne_
  from test.orm import _base, _fixtures
 -from sqlalchemy.test.schema import Table, Column
  from sqlalchemy import event
 +from test.lib.schema import Table, Column
  
  class MergeTest(_fixtures.FixtureTest):
      """Session.merge() functionality"""