In Pennsylvania, independents don’t vote in the primary election; only those registered as Democrat or Republican may vote. At the polls, Republicans get a ballot with Republican-only candidates; Democrats get only Democrat candidates. This way, the parties alone pick the candidate at the top of the ticket. The top vote getters in each party advance to the general election ballot where everyone, including independents, can vote for any candidate. Gov. Tom Wolf’s second term will end in 2022. He cannot run again, meaning that there will be no incumbent advantage in the state’s governor’s race. With only six months to go before the May 17 Pennsylvania primary, the gubernatorial race promises to be snoozefest for Democrats with just one declared Democratic candidate so far, Pennsylvania Attorney General Josh Shapiro. If no challengers appear, Shapiro is a shoo-in to become the Democratic nominee to be placed on the ballot in the …