message: Cities cannot be reduced to 0 population from emigration
diff: @@ -349,7 +349,7 @@ def immigration():
  iNumMigrations = min(sourcePlayers.count() / 4, targetPlayers.count())
  - sourceCities = sourcePlayers.cities().highest(iNumMigrations, getEmigrationValue)
  + sourceCities = sourcePlayers.cities().where(lambda city: city.getPopulation() > 1).highest(iNumMigrations, getEmigrationValue)
  targetCities = targetPlayers.cities().highest(iNumMigrations, getImmigrationValue)
  for sourceCity, targetCity in zip(sourceCities, targetCities):
  