PL/Python: Adjust the regression tests for Python 3.3

The string representation of ImportError changed.  Remove printing
that; it's not necessary for the test.

The order in which members of a dict are printed changed.  But this
was always implementation-dependent, so we have just been lucky for a
long time.  Do the printing the hard way to ensure sorted order.

src/pl/plpython/sql/plpython_import.sql

@@ -4,8 +4,7 @@ CREATE FUNCTION import_fail() returns text
     AS
 'try:
 	import foosocket
-except Exception, ex:
-	plpy.notice("import socket failed -- %s" % str(ex))
+except ImportError:
 	return "failed as expected"
 return "succeeded, that wasn''t supposed to happen"'
     LANGUAGE plpythonu;