patchmode directory

[biruh]

hi, i have Vim 7.2
In my _vimrc file i have
set backup
set backupext=bak
set backupdir=c:\vimbackups
set patchmode=.orig

the backup and patchmode works as expected. But the the patch file is
created in the same directory with the edited file unlike the backups.
I read in the todo list something like set patchmode=c:\vimbackups
\*.orig but doesn't work with an error. I want to save the original
file in c:\vimbackups. Any tips and tricks?
Thanks