unicode backrefs broken on python 2

[Former user]

(original reporter: gazpachoking) It seems that backrefs can no longer be unicode strings on 0.9 in python 2. When they are, the following problem occurs, due to the type check if isinstance(self.backref, str)::

  File "...\sqlalchemy\orm\relationships.py", line 1566, in _generate_backref
    backref_key, kwargs = self.backref
ValueError: too many values to unpack

[Former user]

(original author: gazpachoking) This is an issue when using from __future__ import unicode_literals, don't think it's really a problem otherwise.

[Mike Bayer]

OK that should probably be "isinstance(self.backref, util.string_types), need to take a look.

[Mike Bayer]

6d3e563a575bcdc57c966980abc5038337