ArrayField of IntegerField-s with Choices does not pass validation

[Denis Sumin]

I have an ArrayField with IntegerField inside, and the IntegerField has choices.
Widgets return back a list of strings (instead of a list of integers). That is why the validation fails.
I've found that changing ArrayField.to_python from this

    def to_python(self, value):
        if isinstance(value, six.string_types):
            # Assume we're deserializing
            vals = json.loads(value)
            value = [self.base_field.to_python(val) for val in vals]
        return value

to something like this

    def to_python(self, value):
        if isinstance(value, six.string_types):
            # Assume we're deserializing
            vals = json.loads(value)
            value = [self.base_field.to_python(val) for val in vals]
        elif isinstance(value, list):
            value = [self.base_field.to_python(val) for val in value]
        return value

fixes the problem.

[Marc Tamlyn]

This appears to be a duplicate of #27161