def clean_url(self):
        """
        Validate the input for field *url* checking if the specified
        URL already exists. If it is an actual update and the URL has
        not been changed, validation will be skipped.

        Returns cleaned URL or raises an exception.
        """
        url = self.cleaned_data['url']
        if 'url' != self.changed_data:
            if not url.endswith('/'):
                url += '/'
            URLDoesNotExistValidator()(url)
        return url
dataset/ETHPy150Open django-oscar/django-oscar/src/oscar/apps/dashboard/pages/forms.py/PageUpdateForm.clean_url/operator `in` -> `!=`