[migration] Stop setting session.data['rebuild-infered']
It's no longer read anywhere since fe267b7336f3 "[migration] always
rebuild infered relation"
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))