No WorkingTree exists after branching

[Xue Fuqiao]

And I found another problem (not sure if I should create a new thread,
since the two problems may be associated):

$ bzr up
Tree is up to date at revision 114731 of branch /home/xfq/emacs-repo/main/trunk

But the latest rev for trunk is 114734 instead of 114731.

I've already bound the local trunk to the upstream master by:

   echo "public_branch =
bzr+ssh://xfq@bzr.savannah.gnu.org/emacs/trunk" >>
.bzr/branch/branch.conf
   bzr bind bzr+ssh://xfq@bzr.savannah.gnu.org/emacs/trunk

I read the output of "bzr help {bind, update, pull, working-trees}" and
searched existing FAQs/questions but didn't get anything that looked
promising.  Any ideas?