[rqlrewrite] sort possible types when turning is_instance_of into is
Helps get predictable output even with python -R. Related to #4959402.
import ConfigParser
try:
undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
except ConfigParser.NoOptionError:
pass # this conf. file was probably already migrated
else:
config.global_set_option('undo-enabled', bool(undo_actions))