Subtle Docs & Links trap

[Ravi Pandya <ravi>]

This is an interesting and obscure problem that took me a while to
figure out when it happened, and would be even more obscure to our
developers. If you try and get a waldo on a document and someone else
has it grabbed, you get a waldo on a new bert. If you then try and
backfollow from the ID of the document that you do have to find links
to that document, you will not get anything: since it is a new
document nobody links to it. I think this is correct behavior, but it
can trap the unwary; we should flag it in the documentation.
	--ravi