`check_geonames_date` does not work for smaller geonames data sets

[vks]

I'm using Mordecai with the cities500.zip dump of the geonames database. This makes check_geonames_date crash, because MIT is not part of this subset. Would it be possible to use a different geonames entity for determining the modified date, like New York City (geonameid='5128581') for instance?