test_site often failed under "regrtest.py -r", because this xmlrpc test
left sys with a setdefaultencoding attribute, but loading site.py removes
that attribute and test_site.py verifies the attribute is gone. Changed
this test to get rid of sys.setdefaultencoding if it didn't exist when
this test started.
Don't know whether this is a bugfix (backport) candidate.
imports e.g. test_support must do so using an absolute package name
such as "import test.test_support" or "from test import test_support".
This also updates the README in Lib/test, and gets rid of the
duplicate data dirctory in Lib/test/data (replaced by
Lib/email/test/data).
Now Tim and Jack can have at it. :)