Possible "leftover" attachment in case of MaximumLengthIsReachedError

[lelit]

In the following scenario

class Icon(SA_Image):
    __auto_coercion__ = True
    __max_length__ = 1*MB
    __min_length__ = 1*KB
    __pre_processors__ = (
        ImageAnalyzer(),
        ImageValidator(
            minimum=(16, 16),
            maximum=(600, 600),
            min_aspect_ratio=0.9,
            max_aspect_ratio=1.7777,  # 16/9
            content_types=('image/png', 'image/jpeg', 'image/gif', 'image/webp')),
        ImageProcessor(fmt='png'),
    )
    suffix = ''

when I .attach() an image bigger than 1MB, the code path reaches the store's put method, that in turn calls copy_stream(), which may raise a MaximumLengthIsReachedError exception.

At that point, the error bubbles up and terminate the request, but the incomplete target file is left in the store. I think that the put() method should intercept the error and remove the incomplete file from the store.

I tried to distill a minimal test case, but failed, sorry.