[1.7.x] Ignore through being None on some special cases of fields.
[1.7.x] Ignore through being None on some special cases of fields.

jyotsna1820/django,oscaro/django,jyotsna1820/django,oscaro/django,jyotsna1820/django,jyotsna1820/django,oscaro/django,oscaro/django