title: Rake fails to install on Cygwin
body: <p>We just installed the latest cygwin (setup version: 2.891 - 64bit on the latest Windows 10) and we've installed rvm (1.29.4) and whenever we run <code>bundle install</code> we obtain the following error:</p>
  
  <pre><code>Encoding::CompatibilityError: incompatible character encodings: ASCII-8BIT and UTF-8
  An error occurred while intalling rake (12.3.1), and Bundler cannot continue.
  Make sure that 'gem install rake -v '12.3.1' --source 'https://rubygems.org/'' succeeds before bundling.
  </code></pre>
  
  <p>A version of the same error appears when simply <code>gem install rake</code> and there is no stack trace or further indication of where the error lies. How do I proceed with tracking this down? Is there an error log I should be looking at? Where is the encoding mismatch being generated by <code>gem install</code>?</p>
  
  <p>Thanks!</p>