failed with error 13 / failed with error 16550: "not authorized for query"

[chrisckchang]

Using the MongoLab flip-flop tool (http://mongolab.org/flip-flop/) which fails over every 60 seconds, Moped continuously fails with error after 3-4 failovers.

Reproduce:
https://gist.github.com/chrischang12/4dfe58308154e3054426

[zarqman]

Thanks for the script! Super helpful to me in creating patches for #324.

[dblock]

Related #322.