title: How do I update a gem to a specific version on the command line?
body: <p>I'm using Rails 4.2.3.  I would like to update a specific gem (rspec) on the command line, however I can't seem to get it to work.</p>
  <pre><code>$ bundle update rspec-rails -version 3.9
  No value provided for option '--retry'
  $ bundle update rspec-rails -version 3.9 --retry==1
  No value provided for option '--retry'
  $ bundle update rspec-rails -version 3.9 --retry=1
  No value provided for option '--retry'
  </code></pre>
  <p>What's the right way to update a gem to a specific version using the bin/bundle command line tool?</p>