     if isOwner user, this
       return callback null
 
-    options = target: [user.username], asUser: no
+    options = target: [user.username], asUser: no, permanent: yes
 
     @shareWith options, (err)->
       callback err

      @update $set: { users }, (err)-> callback err


  removeUsers: (usersToRemove, callback)->

    users = @users.splice 0

    for user in usersToRemove
      users = excludeUser users, user

    @update $set: { users }, (err)-> callback err


    return owner


  excludeUser = (options)->

    { users, user, permanent } = options

    userId   = user.getId()
    newUsers = []

    for u in users
      if u.permanent isnt permanent or not userId.equals u.id
        newUsers.push u

    return newUsers

