title: "cannot load such file -- rubygems/defaults/operating_system" when installing Ruby 2.0.0
body: <p>I have need of Ruby 2.0.0, so I turned to RVM to help manage my ruby installations.</p>
  
  <p>However, when I do <code>rvm install ruby-2.0.0</code>, the installation ends up bombing out. </p>
  
  <pre><code>$ rvm install ruby-2.0.0
  Searching for binary rubies, this might take some time.
  No binary rubies available for: osx/10.12/x86_64/ruby-2.0.0-p648.
  Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
  Checking requirements for osx.
  Certificates bundle '/usr/local/etc/openssl/cert.pem' is already up to date.
  Requirements installation successful.
  Installing Ruby from source to: /Users/nick/.rvm/rubies/ruby-2.0.0-p648, this may take a while depending on your cpu(s)...
  ruby-2.0.0-p648 - #downloading ruby-2.0.0-p648, this may take a while depending on your connection...
  ruby-2.0.0-p648 - #extracting ruby-2.0.0-p648 to /Users/nick/.rvm/src/ruby-2.0.0-p648....
  ruby-2.0.0-p648 - #applying patch /Users/nick/.rvm/patches/ruby/2.0.0/openssl3.patch.
  ruby-2.0.0-p648 - #applying patch /Users/nick/.rvm/patches/ruby/2.0.0/update-autoconf.patch.
  ruby-2.0.0-p648 - #configuring.................................................
  ruby-2.0.0-p648 - #post-configuration.
  ruby-2.0.0-p648 - #compiling...................................................|
  ruby-2.0.0-p648 - #installing..............
  ruby-2.0.0-p648 - #making binaries executable..
  ruby-2.0.0-p648 - #downloading rubygems-2.7.2
  ruby-2.0.0-p648 - #extracting rubygems-2.7.2.....
  ruby-2.0.0-p648 - #removing old rubygems........
  ruby-2.0.0-p648 - #installing rubygems-2.7.2.
  Error running 'env GEM_HOME=/Users/nick/.rvm/gems/ruby-2.0.0-p648@global GEM_PATH= /Users/nick/.rvm/rubies/ruby-2.0.0-p648/bin/ruby -d /Users/nick/.rvm/src/rubygems-2.7.2/setup.rb --no-document',
  please read /Users/nick/.rvm/log/1510703598_ruby-2.0.0-p648/rubygems.install.log
  </code></pre>
  
  <p>So, I check out the log file as instructed, and this is what I see:</p>
  
  <pre><code>[2017-11-14 15:55:25] /Users/nick/.rvm/rubies/ruby-2.0.0-p648/bin/ruby
  current path: /Users/nick/.rvm/src/rubygems-2.7.2
  PATH=/usr/local/opt/coreutils/bin:/usr/local/opt/pkg-config/bin:/usr/local/opt/libtool/bin:/usr/local/opt/automake/bin:/usr/local/opt/autoconf/bin:/Users/nick/.nvm/versions/node/v8.4.0/bin:/usr/local/sbin:/usr/local/bin:/Users/nick/.gvm/vertx/current/bin:/Users/nick/.gvm/springboot/current/bin:/Users/nick/.gvm/lazybones/current/bin:/Users/nick/.gvm/jbake/current/bin:/Users/nick/.gvm/groovyserv/current/bin:/Users/nick/.gvm/groovy/current/bin:/Users/nick/.gvm/griffon/current/bin:/Users/nick/.gvm/grails/current/bin:/Users/nick/.gvm/gradle/current/bin:/Users/nick/.gvm/glide/current/bin:/Users/nick/.gvm/gaiden/current/bin:/Users/nick/.gvm/crash/current/bin:/usr/local/mongodb_2.4.5/bin:/Users/nick/.gvm/grails/current/bin:/usr/local/mysql/bin:/Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home/bin:/usr/local/mongodb_2.4.5/bin:/Users/nick/.gvm/grails/current/bin:/usr/local/scala-2.12.1/bin:/usr/local/mysql/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/share/dotnet:/usr/local/git/bin:/Library/Frameworks/Mono.framework/Versions/Current/Commands:/Users/nick/.rvm/bin
  command(7): env GEM_HOME=/Users/nick/.rvm/gems/ruby-2.0.0-p648@global GEM_PATH= /Users/nick/.rvm/rubies/ruby-2.0.0-p648/bin/ruby -d /Users/nick/.rvm/src/rubygems-2.7.2/setup.rb --no-document
  Exception `LoadError' at /Users/nick/.rvm/rubies/ruby-2.0.0-p648/lib/ruby/2.0.0/rubygems.rb:1087 - cannot load such file -- rubygems/defaults/operating_system
  Exception `LoadError' at /Users/nick/.rvm/rubies/ruby-2.0.0-p648/lib/ruby/2.0.0/rubygems.rb:1096 - cannot load such file -- rubygems/defaults/ruby
  YAML safe loading is not available. Please upgrade psych to a version that supports safe loading (&gt;= 2.0).
  Bundler 1.16.0 installed
  RubyGems 2.7.2 installed
  Regenerating binstubs
  </code></pre>
  
  <p>I'm not really sure what to make of this error. I've tried uninstalling 2.0.0 and installing it again, imploding &amp; reinstalling rvm, even reinstalling ruby with homebrew and doing everything from scratch, but this error persists. Any ideas?</p>