Bug Report: hg {copy, rename, mv} with ".." to an empty directory fails with obscure error

[Mike Neuman]

Matt Mackall wrote:
> Can you try adding some debugging prints to
> mercurial/util.py:canonpath and see if you can catch it doing
> something obviously dumb?

   Nothing obviously dumb, but notice that the error message is when 
python tries to stat the destination file, which doesn't exist.

% hg mv file1 ../dir2
abort: /home/mcn/test-rep/dir2/file1 not under root

   The cause of this error is an OSError exception thrown when os.stat() 
is called with the non-existent destination file.

The OSError is:
[Errno 2] No such file or directory: '/home/mcn/test-rep/dir2/file1'

   I'm happy to keep tracking this down if you have more suggestions.

-Mike