- Fixed bug where using a :class:`.TypeDecorator` that implemented
a type that was also a :class:`.TypeDecorator` would fail with
Python's "Cannot create a consistent method resolution order (MRO)"
error, when any kind of SQL comparison expression were used against
an object using this type.

(cherry picked from commit d1ac6cb33af3b105db7cdb51411e10ac3bafff1f)