ImageField with core=True: working as intended or bug?

[Jenan Wise]

I have a many to one relationship:

class Album(meta.Model):
    # ...

class Picture(meta.Model):
    album = meta.ForeignKey(Album, edit_inline=meta.TABULAR)
    image = ImageField(upload_to="pictures/")
    # ...

The only core field for Picture is image. However, this seems to
automatically delete each Picture after the album has been saved.  I
assume this is because even though image is not empty for saved
pictures, the image form field itself is cleared each time. (?)

Is this a bug, or working as intended?

Sorry if this has been covered already.  I couldn't find anything.

Thanks!