SAN FRANCISCO — Two former prison chiefs handpicked by Gov. Arnold Schwarzenegger said Wednesday that election-year politics had thwarted their efforts to fix the crisis gripping California's correctional system, prompting them to resign in frustration earlier this year. Testifying in federal court, the two corrections secretaries singled out the prison guards union and a pair of Schwarzenegger's top aides for most of the blame, saying the aides had given the union veto power over candidates for top jobs and a say in other key decisions. One of the aides, Chief of Staff Susan Kennedy, said she planned to play a...