title: "Could not find rake-12.3.3 in any of the sources."
body: <p>I tried running these commands:</p>
  
  <pre><code>gem uninstall rake
  rm Gemfile.lock
  bundle install
  gem install rake --version=12.3.3
  </code></pre>
  
  <p>I also tried adding rake 12.3.3 to the gemfile and running <code>bundle install</code>:</p>
  
  <pre><code>gem 'rake', '12.3.3'
  </code></pre>
  
  <p>This is my Dockerfile:</p>
  
  <pre><code>FROM ruby
  
  RUN apt-get update -qq &amp;&amp; apt-get install -y build-essential
  
  # for postgres
  RUN apt-get install -y libpq-dev
  
  # for nokogiri
  RUN apt-get install -y libxml2-dev libxslt1-dev
  
  # for a JS runtime
  RUN apt-get install -y nodejs
  
  ENV APP_HOME /readpaths
  WORKDIR $APP_HOME
  
  ADD Gemfile* $APP_HOME/
  RUN bundle install
  
  ADD . $APP_HOME
  </code></pre>
  
  <p>I've just noticed something curios: No matter how often I run <code>gem uninstall rake</code> (I tried five times) I always get a message saying:</p>
  
  <pre><code>Successfully uninstalled rake-12.3.1
  </code></pre>
  
  <p>When I run gem install rake I get:</p>
  
  <pre><code>Successfully installed rake-12.3.3
  </code></pre>
  
  <p>Then, when I run gem uninstall rake again, I get again:</p>
  
  <pre><code>Successfully uninstalled rake-12.3.1
  </code></pre>