Comment 101 for bug 1546507

Was doing some more thinking about the Mike/Fei Long patch.

I'm worried about the image_locations_with_url() function. Isn't
it going to trigger a full scan of the image_locations table for
each delete? That seems like a very expensive operation.

The other thing that occurred to me was that in the swift case,
a malicious user could set the image location to a segment of a
public image. If the segment were deleted, the entire image would
be rendered useless. I guess what I'm getting at is that if this
function only covers some cases, maybe we shouldn't include it,
especially since it seems very expensive.

What do you think?