[Sqlalchemy-tickets] Issue #3630: inconsistency in concrete relationships w/ name overlap in relationship() vs. backref (zzzeek/sqlalchemy)

[Mike B. <iss...@bi...>]

New issue 3630: inconsistency in concrete relationships w/ name overlap in relationship() vs. backref
https://bitbucket.org/zzzeek/sqlalchemy/issues/3630/inconsistency-in-concrete-relationships-w

Mike Bayer:

this is extracted from #3022.  test:

```
#!python

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

err = True

class A(Base):
    __tablename__ = 'a'
    id = Column(Integer, primary_key=True)

    if not err:
        b = relationship("B", foreign_keys="B.a_id", backref="a")


class A1(A):
    __tablename__ = 'a1'
    id = Column(Integer, primary_key=True)

    if not err:
        b = relationship("B", foreign_keys="B.a1_id", backref="a1")
    __mapper_args__ = {'concrete': True}


class B(Base):
    __tablename__ = 'b'
    id = Column(Integer, primary_key=True)

    a_id = Column(ForeignKey('a.id'))
    a1_id = Column(ForeignKey('a1.id'))

    if err:
        a = relationship("A", backref="b")

        a1 = relationship("A", backref="b")

configure_mappers()
```