[Sqlalchemy-tickets] Issue #3472: run _postfetch() for post_update to expire onupdates (zzzeek/sqlalchemy)

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

New issue 3472: run _postfetch() for post_update to expire onupdates
https://bitbucket.org/zzzeek/sqlalchemy/issue/3472/run-_postfetch-for-post_update-to-expire

Mike Bayer:

right now onupdates aren't caught


```
#!python

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

Base = declarative_base()

from itertools import count

value = count()


class A(Base):
    __tablename__ = 'a'
    id = Column(Integer, primary_key=True)
    favorite_b_id = Column(ForeignKey('b.id'))
    bs = relationship("B", primaryjoin="A.id == B.a_id")
    favorite_b = relationship(
        "B", primaryjoin="A.favorite_b_id == B.id", post_update=True)
    updated = Column(Integer, onupdate=lambda: next(value))


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

e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)

s = Session(e)
a1 = A()
b1 = B()

a1.bs.append(b1)
a1.favorite_b = b1
s.add(a1)
s.flush()
assert a1.updated == 0, a1.updated

```

this is definitely for 1.1 at earliest