title: Bundler 2.0.1 installed, Rails says "must use Bundler 2 or greater"?
body: <p>I'm a Rails newb who's trying out Rails on a DigitalOcean droplet. The installations seemed to work fine, but I'm getting a curious error message when I try to generate a scaffold:</p>
  
  <pre><code>DO 10:48 Rails/simple (master) → rails generate scaffold User name:string email:string
  Traceback (most recent call last):
          5: from bin/rails:3:in `&lt;main&gt;'
          4: from bin/rails:3:in `load'
          3: from /home/tony/rails/simple/bin/spring:10:in `&lt;top (required)&gt;'
          2: from /home/tony/rails/simple/bin/spring:10:in `new'
          1: from /home/tony/.rvm/rubies/ruby-2.6.0/lib/ruby/2.6.0/bundler/lockfile_parser.rb:95:in `initialize'
  /home/tony/.rvm/rubies/ruby-2.6.0/lib/ruby/2.6.0/bundler/lockfile_parser.rb:108:in `warn_for_outdated_bundler_version': You must use Bundler 2 or greater with this lockfile. (Bundler::LockfileError)
  DO 10:49 Rails/simple (master) → bundle list bundler
  /home/tony/.rvm/gems/ruby-2.6.0/gems/bundler-2.0.1
  DO 10:50 Rails/simple (master) → gem list bundler
  
  *** LOCAL GEMS ***
  
  bundler (2.0.1, default: 1.17.2)
  bundler-unload (1.0.2)
  rubygems-bundler (1.4.5)
  </code></pre>
  
  <p>I.e., the current Bundler gem is version 2.0.1, but Rails still thinks it's insufficient.</p>
  
  <p>I can't find anything similar on the web. The only red flag I can see is that the bundler gem shows a default version of 1.17.2. How do I begin to diagnose the problem?</p>