Over the past 30 years, the District has passed innumerable gay-rights milestones. But when it comes to passing one of the very last — electing the city’s first openly gay mayor -- many gay Democratic activists say they can wait. The choice between gay independent David A. Catania and straight Democrat Muriel Bowser illuminates the state of identity politics in modern-day D.C., where LGBT political solidarity is not what it was in, say, 1978 when the gay vote thrust Marion Barry into office.