regression in CAST behavior due to type_coerce enhancement

[Mike Bayer]

works in 0.8, fails in 0.9:

from sqlalchemy import *

class MyType(TypeDecorator):
    impl = Unicode

type_ = MyType()

value = cast(literal("hi", type_), Unicode)
assert value.clause.type is type_  # <- becomes unicode, MyType is lost

[Mike Bayer]

cac7320eeb16e62f347dbf009

[Mike Bayer]

Removing milestone: 0.9.0 (automated comment)