No-one uses 1.9.1 or 1.9.0 - they have weird bugs and I remember people very quickly switching to 1.9.2 (much faster than they switched 1.9.2 -> 1.9.3).

I stole this from `factory_girl`'s gemspec: https://github.com/thoughtbot/factory_girl/blob/master/factory_girl.gemspec#L17