Simple reproducer for transient ASDF bug

asdf_test_case.py

#!/usr/bin/env python
import asdf
from astropy import units as u
from astropy.coordinates.representation import SphericalRepresentation

tree = {'coord': SphericalRepresentation(10*u.deg, 10*u.deg, 1*u.m)}
print('distance:', tree['coord'].distance)

with asdf.AsdfFile(tree=tree) as ff:
    ff.write_to("test.asdf")

with open('test.asdf', 'rb') as ff:
    data = ff.read()
    try:
        print(data.decode('ascii'))
    except UnicodeDecodeError:
        index = data.find(b'\xd3BLK')
        print(data[:index].decode('ascii'))
        print(data[index:])