Augment test coverage in PL/Python, especially for error conditions.

src/pl/plpython/sql/plpython_test.sql

@@ -19,3 +19,18 @@ return words'
 	LANGUAGE plpythonu;
 
 select argument_test_one(users, fname, lname) from users where lname = 'doe' order by 1;
+
+
+CREATE FUNCTION elog_test() RETURNS void
+AS $$
+plpy.debug('debug')
+plpy.log('log')
+plpy.info('info')
+plpy.info(37)
+plpy.info('info', 37, [1, 2, 3])
+plpy.notice('notice')
+plpy.warning('warning')
+plpy.error('error')
+$$ LANGUAGE plpythonu;
+
+SELECT elog_test();