after turnining on mongodb auth..subsequent runs fail

If I setup mongodb 2.6 with auth enabled and add an admin user with appropiate roles, any subsequent provision run with Vagrant will lead to authorization errors. I try'd to give the literal auth string to the mong_eval function, but it won't work.

I also put the issue on serverfault: http://serverfault.com/questions/665688/mongodb-authentication-not-working-in-puppet

thanks