[Bug] InMemoryFileNode has no attribute "name"

[David]

Using the InMemoryStorage into an other model by using:

# models.py

class MyModel(models.Model):
    attachment = models.FileField(...)

# script.py

obj = MyModel.objects.create(attachment=ContentFile(b'content', 'myfile.txt') 
repr(obj.attachment)

An excetption is raised: AttributeError("'InMemoryFileNode' object has no attribute 'name'") raised in repr()

This may be caused by the fact that InMemoryFileNode inheriths from ContentFile but does not use the name attribute nor uses the base class __init__ method:

​https://github.com/django/django/blob/509763c79952cde02d9f5b584af4278bdbed77b2/django/core/files/storage/memory.py#L48-L52

This resulting in a partially initialized object without an important property.