Allow formfield_overrides to contain field names too.

def formfield_for_dbfield(self, db_field, **kwargs):
        """
        Allow formfield_overrides to contain field names too.
        """
        overrides = self.formfield_overrides.get(db_field.name)
        if overrides:
            kwargs.update(overrides)

        field = super(AbstractEntryBaseAdmin, self).formfield_for_dbfield(db_field, **kwargs)

        # Pass user to the form.
        if db_field.name == 'author':
            field.user = kwargs['request'].user
        return field