[PATCH] Fix util._statfiles_clustered() failing at root of awindows drive

[Andrei Vermel]

> I cannot reproduce with or without osutil.pyd. Is it 2.4.3 vs 
> 2.4.4 ? ActiveState vs non-ActiveState ? Looks unlikely. I'd 
> really like to understand what's going wrong instead of 
> patching blindly. I suppose the failure comes from 
> osutil.listdir() when called with drive paths ? Does it fail 
> with the C extension or without or in both cases ?
> 

dir, base = nf[:pos], nf[pos+1:]
with nf="m:\qqq.txt" gives dir="m:"

When cwd = "m:\", this works fine, because "m:" means cwd.
When cwd is a subfolder, things go wrong.
Adding os.sep to "m:" fixes this.

Andrei