I traced this behaviour to the patch at revision 425 in
the repository; at rev 422 it works, and at 425 it doesn't.
My object gets its 'location' attribute set, and the
function _set_location reads the file at that location
and sets a few other attributes within that function.
The behaviour I'm seeing is that these attributes are
being set during the function, but when the object is
referenced later, the default value (as specified when
the column is defined) is returned.
There's a short example attached, that's slightly
contrived to demonstrate the structure of the object,
but runs here. The output of such a program at rev 425
is None and at 422 is "a string"