Not so much a bug as a feature, but on editing one of Kichae's graphs from this post:
into this post (directly above it):
it seems the System automatically edited my post to use a locally saved copy of the image.
Why am I posting about this here when it's so obviously a feature? Well, as I said I got the image, and it's link, from Kichae's post. Pretty sure it was locally saved then, too. Seems kind of silly to double the storage and bandwidth used, even if it really doesn't matter much.