The Oakland Public Ethics Commission voted 3-1 last night against a proposal by City Attorney John Russo to double the contribution limits in city election campaigns. However, the ethics commission’s vote is not binding, and Russo’s plan will now likely be taken up by the Oakland City Council later this month. Russo’s proposal is generally viewed as a boost for the mayoral candidacy of Don Perata, a prodigious fund-raiser who has deep-pocketed donors, while being bad news for Perata’s main opponent, Councilwoman Jean Quan, who is mounting a grassroots campaign.