If buftype=acwrite, Vim doesn't adjust relative buffer names when
changing directory. Since 5103285d, encrypted buffers have set
buftype=acwrite and therefore also risked having incorrect buffer names
(e.g., if 'autochdir' is set).
Now that the buffer name is always fully resolved, this should no longer
be a problem.
Closesjamessan/vim-gnupg#81
Signed-off-by: James McCoy <jamessan@jamessan.com>