Aimee Mann knows a sinking ship when she sees one. And she saw the holes in the ballast back at the turn of the century when she asked for her release from her record company so that she could release “Bachelor No. 2 or, The Last Remains of the Dodo” herself. It’s not so much that the majors were going down (Interscope, the label she was signed to at the time, has soldiered on fine without her) so much as the marriages between these companies and a classic breed of singer/songwriters going down for the count. In asking for, and receiving, her exit, she was getting a few years’ head start on nearly every other significant artist of a similarly artisan ilk also looking to go independent, either out of choice or necessity.