lib/flor/core/executor.rb
def leave_tags(message, node)

      ts = node['tags']; return [] unless ts && ts.any?

      [ { 'point' => 'left',
          'tags' => ts,
          'exid' => exid,
          'nid' => node['nid'],
          'payload' => message['payload'] } ]
    end
def leave_tags(message, node)

      ts = node['tags']; return [] unless ts && ts.any?

      [ { 'point' => 'left',
          'tags' => ts,
          'exid' => exid,
          'nid' => node['nid'],
          'payload' => message['payload'] } ]
    end
This saves the modified trees in the parent when the node is removed
 it works ok except for 3 (2017-05-9) failing specs.

 Introducing 3 exceptions for this is not interesting.

    def update_parent_node_tree(node)

      t = node['tree']; return unless t
return if t[0] == '_apply'
      pnode = @execution['nodes'][node['parent']]; return unless pnode

      pt =
        pnode['tree'] ||
        Flor::Node.new(self, pnode, nil).lookup_tree(pnode['nid'])
      cid =
        Flor.child_id(node['nid'])

      if cid == pt[1].size # head "exception"
        return if pt[0] == t
        pt[0] = t
        pnode['tree'] = pt
        return
      end

      pt[1][cid] = t
      pnode['tree'] = pt
    end