Logged In: YES 
user_id=580015

I've revised the patch; ignore the old one.  This version
includes a vastly expanded test_tempfile.py which hits every
line that I know how to test.  The omissions are marked -
it's mostly non-Unix issues.

Also, I went through the entire CVS repository and replaced
all uses of tempfile.mktemp with
mkstemp/mkdtemp/NamedTemporaryFile,
as appropriate.  The sole exception is Lib/os.py, which is
addressed by patch #590294.

The sole functional change to tempfile.py itself, from the
previous, is to throw os.O_NOFOLLOW into the open flags. 
This closes yet another hole - on some systems, without this
flag, open(file, O_CREAT|O_EXCL) will follow a symbolic link
that points to a nonexistent file, and create the link
target.  (This has no effect on a symlink in the directory
components of the pathname - if the sysadmin has symlinked
/tmp to /hugedisk/scratch, that still works.)