pid across threads (but in that case, it's still the same process, and so
still sharing the "template" cache in tempfile.py).  Repaired that, and
added a new std test.
On Linux, someone please run that standalone with more files and/or more
threads; e.g.,

    python lib/test/test_threadedtempfile.py -f 1000 -t 10

to run with 10 threads each creating (and deleting) 1000 temp files.