The loop to add buttons was merged into persona. A similar addition should probably be added to vanilla.
I now add buttons in my plugin via hook filter:post.getPosts and in the hook:
Plugin.postsBuild = function(params, cb) { var histButton = {action: 'posts/edithistory', icon: 'fa-file-text', html: 'Edit History'}; async.map(params.posts, function(post, next) { if(!post) return next(); if(!!post.tools) { post.tools = []; } post.tools.push(histButton); }); cb(null, params); };