[i18ncube] fix crash due to duplicated messages in generated schema.pot
Add a test case and fix regression introduced in e713c47a993d.
Relates to #2811282
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))