title: docker-compose run command cannot find gem after running bundle install
body: <p>I'm using docker-compose for my rails app.</p>
  
  <p>I recently pulled in updates to my master branch that updated the rails version to 5.2.3 -- and I ran bundle install via docker-compose:</p>
  
  <p><code>docker-compose run web bundle install</code></p>
  
  <p>Seemed like it ran fine, but then when I try to run rspec I get this error:</p>
  
  <pre><code>Could not find activesupport-5.2.3 in any of the sources
  Run `bundle install` to install missing gems.
  </code></pre>
  
  <p>I try to run <code>bundle update activesupport</code> - and get this:</p>
  
  <pre><code>Bundler attempted to update activesupport but its version stayed the same
  Bundle updated!
  </code></pre>
  
  <p>So I try to install the gem manually:</p>
  
  <pre><code>docker-compose run web gem install activesupport
  Fetching activesupport-5.2.3.gem
  Successfully installed activesupport-5.2.3
  1 gem installed
  </code></pre>
  
  <p>Then I try to run rspec again, and same thing:</p>
  
  <pre><code>$ docker-compose run web bin/rspec ./spec/some_spec.rb 
  Could not find activesupport-5.2.3 in any of the sources
  Run `bundle install` to install missing gems.
  </code></pre>
  
  <p>Is docker-compose not picking up on the gem/bundler changes? Am I missing something here?</p>