- The OS X version of mktemp doesn't support the --tmpdir flag.
- According to the doc for mktemp on OSX: "If no arguments are passed or if only the -d flag is passed mktemp behaves as if -t tmp was supplied."
- This will continue to work for Linux based versions of mktemp.
Signed-off-by: Cody W. Eilar <ecody@vmware.com>