correct response code to BIND / REBIND when source is not found?

Hello,

In the case of a BIND or REBIND, what is the correct response code
when the resource specified in the href element is not found?
(preconditions DAV:bind-source-exists and DAV:rebind-source-exists.)
I figure since it's not the Request-URI, the response should not be
404.  I see two options: a 207 Multistatus with an inner status of 404
on the href, or a 409 Conflict.  Any idea which, or if it's a totally
different response code?

Thanks,
Tim