vc-next-action sometimes does the Wrong Thing in branches

[Gustav Hållberg]

In GNU Emacs 21.3.1 (i686-pc-linux-gnu, X toolkit):

If one is editing a CVS'ed file in a CVS branch and someone else commits a
change to that file (on that branch), and does vc-next-action, one is asked:

   foofile is not up-to-date.  Get latest version? (yes or no) 

and if you answer "yes", the most recent version _from the main branch_ is
fetched. This is incorrect. The Right Thing should be to fetch the most recent
version _on that branch_.

- Gustav