Comment 0 for bug 266572

The existing code in HyperDatabase.py looks like it
was intending to fallback to threading by subject if
the In-Reply-To and References headers were missing.

However the implementation it is broken, apparently
an incomplete port of some other module.

This patch fixes the set_location() method, and
getOldestArticle methods to allow subject threading
to once again work.

Note: pipermail.py has an unused database class which
also implements broken versions of these methods. This
patch does not fix those because they were unused.

[http://sourceforge.net/tracker/index.php?func=detail&aid=509269&group_id=103&atid=300103]