Vagrant is now packaged in Fedora 21 and later versions, which is great news. No more messing around with the horror of rvm!

After installing vagrant and the libvirt plugin with yum:

$ sudo yum install vagrant vagrant-libvirt

I got some syntax errors from Vagrant:

$ vagrant up
/usr/share/vagrant/lib/vagrant/pre-rubygems.rb:19:in `require_relative': /usr/share/vagrant/lib/vagrant/bundler.rb:217: syntax error, unexpected tPOW (SyntaxError)
    def internal_install(plugins, update, **extra)
                                            ^
/usr/share/vagrant/lib/vagrant/bundler.rb:298: class definition in method body
/usr/share/vagrant/lib/vagrant/bundler.rb:315: class definition in method body
/usr/share/vagrant/lib/vagrant/bundler.rb:368: syntax error, unexpected keyword_end, expecting $end
    from /usr/share/vagrant/lib/vagrant/pre-rubygems.rb:19:in `<main>'

This was caused by rvm having an old version of ruby installed, which is what was installed when I installed vagrant on this machine initially:

$ ruby --version
ruby 1.9.3p545 (2014-02-24 revision 45159) [x86_64-linux]

Luckily you can just:

$ rvm implode

and everything will be happy, where happy is defined by vagrant running and having the fewest versions of ruby installed.