Using rbenv, I'm trying to use rails 5.1.0-alpha but something is fucked

output

[Neils-MacBook-Pro rails (master *>)]$ rbenv rehash
[Neils-MacBook-Pro rails (master *>)]$ which rails
/Users/neil/.rbenv/shims/rails
[Neils-MacBook-Pro rails (master *>)]$ which gem
/Users/neil/.rbenv/shims/gem
[Neils-MacBook-Pro rails (master *>)]$ rails -v
Rails 4.2.6
[Neils-MacBook-Pro rails (master *>)]$ gem uninstall rails

Select gem to uninstall:
 1. rails-5.0.0.rc1
 2. rails-5.1.0.alpha
 3. All versions
 
[Neils-MacBook-Pro rails (master *>)]$ gem list rails

*** LOCAL GEMS ***

coffee-rails (4.1.1, 4.1.0)
jquery-rails (4.1.1, 4.0.5)
rails (5.1.0.alpha, 5.0.0.rc1)
rails-deprecated_sanitizer (1.0.3)
rails-dom-testing (2.0.0, 1.0.7)
rails-html-sanitizer (1.0.3, 1.0.2)
rspec-rails (3.4.2)
sass-rails (5.0.4)
sprockets-rails (3.0.4, 2.3.3)