Interaction between clone and Control pseudo-header

Hi!

I just used a clone in a Control pseudo-header and was wondering
what would happen if one used something like this (didn't want to
try in fear of possibly messing up the bug report):

  Control: clone -1
  Control: retitle -1 new title
  Control: reassign -1 new package

Would the -1 shadow the current bug number, would that fail or would
it be kept referring to it? I guess it would be nice to document that
in bugs.debian.org.

thanks,
guillem