py2k: accept unicode literals on :func:`backref`, toopr/212

Fixed bug where in Py2K a unicode literal would not be accepted as the
string name of a class or other argument within declarative using
:func:`.backref` on :func:`.relationship`.

amends commit e6f67f48054d906856f879bc1803ea639aa4b670

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/sqlalchemy/ext/declarative/clsregistry.py b/lib/sqlalchemy/ext/declarative/clsregistry.py
index c3887d6cf..050923980 100644
--- a/lib/sqlalchemy/ext/declarative/clsregistry.py
+++ b/lib/sqlalchemy/ext/declarative/clsregistry.py
@@ -321,7 +321,8 @@ def _deferred_relationship(cls, prop):
             key, kwargs = prop.backref
             for attr in ('primaryjoin', 'secondaryjoin', 'secondary',
                          'foreign_keys', 'remote_side', 'order_by'):
-                if attr in kwargs and isinstance(kwargs[attr], str):
+                if attr in kwargs and isinstance(kwargs[attr],
+                                                 util.string_types):
                     kwargs[attr] = resolve_arg(kwargs[attr])
 
     return prop