According to the [Tempfile docs](http://www.ruby-doc.org/stdlib-1.9.3/libdoc/tempfile/rdoc/Tempfile.html) the default is not hardcoded to `/tmp`, it is the return value of `Dir.tmpdir`. This is important, because the [tmpdir method](http://ruby-doc.org/stdlib-1.9.3/libdoc/tmpdir/rdoc/Dir.html#method-c-tmpdir) follows the OS and environment temp dir overrides.

One option could be overriding the tmp dir setting for the entire puppet run.

For purposes of this PR, please replace `'/tmp'` with `Dir.tmpdir` in the live above :)