Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Steps to reproduce

1. UseSearchFilter with serializer that has related field to RelatedModel
2. Set search_fields = ('related_model__field', 'my_field')

Expected behavior

Correct filtering

Actual behavior

Raises "RelatedModel" has no field named 'my_field'

I will submit pull request that fix this error. It is caused by overwriting opts in SearchField.must_call_distinct