Gov. Bruce Rauner has called for dramatic legal changes to reduce the prison population.But a bill to decriminalize possession of small amounts of marijuana, the Republican governor announced, is too dramatic.Rauner issued an amendatory veto of House Bill 218, calling for a higher fine for possession of cannabis and a lower threshold for driving under the influence of cannabis. He also said the threshold for criminal possession of marijuana in the bill should be reduced.The state constitution says that the governor may …