An important pension bill is under consideration by lawmakers in Rhode Island — one that has the potential to make history. Gov. Lincoln Chafee and Treasurer Gina Raimondo told a legislative panel earlier this week that their proposal, which would raise the retirement age, suspend COLA subsidies for 19 years, and combine 401(k)-style accounts with traditional pensions, would save taxpayers billions of dollars while making the retirement system viable for public workers. The changes are expected to save taxpayers $3 billion over 10 years. But the picture’s not completely rosy: Unions are fighting the changes and promise to sue the state if the law is enacted.