Looking into printer driver issues, I ran across some peculiarities in

Looking into printer driver issues, I ran across some peculiarities in
copy_file():
- Firstly, if the source file is zero bytes, NT_STATUS_DISK_FULL is
  returned.
- Secondly, the conditional lseek is confusing. It fires when
  OPENX_FILE_EXISTS_OPEN is set and I can't see why the lseek is
  necessary in this case.
- Finally, the lseek error path also results in NT_STATUS_DISK_FULL.

Proposed fix for first and third point below.

Autobuild-User: Jeremy Allison <jra@samba.org>
Autobuild-Date: Thu Jan 27 00:59:56 CET 2011 on sn-devel-104