Storage save method wraps StringIO in File object which is identified as False.

[Maxim Novikov]

​https://github.com/django/django/blob/master/django/core/files/storage.py#L50

class Storage(object):

    def save(self, name, content, max_length=None):
        ...
        if not hasattr(content, 'chunks'):
            content = File(content)

Underlying libraries may use following pattern of code:

def store(data, name):
     data = data or ''

But File object without a name resolved into False which can produce bugs.
Possibly better to pass a name to File object. To ensure bool(content) is True

    if not hasattr(content, 'chunks'):
        content = File(content, name=name)