Guide to alternative expected files:

plpython_error_0.out			Python 2.4 and older

plpython_unicode.out			server encoding != SQL_ASCII
plpython_unicode_3.out			server encoding == SQL_ASCII

plpython_subtransaction_0.out	Python 2.4 and older (without with statement)
plpython_subtransaction_5.out	Python 2.5 (without with statement)

plpython_types_3.out			Python 3.x

Note: Building with Python 2.2 is supported, but there are no expected
files for it (too much work to maintain).
