title: "can't modify frozen string" when running gem on file $RUBY_HOME/rubygems/version.rb
body: <p>I compiled ruby 1.9.3-p134 from source on RedHat RHEL 5.2. </p>
  
  <p>Everything went smoothly except two things. </p>
  
  <p><strong>1</strong>
  When trying to run ruby from the command line it said not found in /usr/bin/ruby, but <code>which ruby</code> pointed to <code>/usr/local/bin/ruby</code>. So i created a softlink <code>ln -s /usr/local/bin/ruby /usr/bin/ruby</code>, however ...</p>
  
  <p><strong>2</strong>
  gem gives me the following error: </p>
  
  <p><code>$ gem</code></p>
  
  <pre><code>/usr/local/lib/ruby/1.9.1/rubygems/version.rb:191:in `strip!': can't modify frozen String (RuntimeError)
         from /usr/local/lib/ruby/1.9.1/rubygems/version.rb:191:in `initialize'
         from /usr/bin/gem:14:in `new'
         from /usr/bin/gem:14:in `&lt;main&gt;'
  </code></pre>
  
  <p>No luck googling since "can't modify frozen String" is a common ruby error. </p>
  
  <p>Any help would be appreciated. </p>