title: Observable finally not getting fired
body: <p>This works:</p>
  
  <pre><code>this.http.get('/doesntexist1')
    .finally(() =&gt; console.log('finally1'))
    .subscribe(() =&gt; { });
  </code></pre>
  
  <p>But this doesn't:</p>
  
  <pre><code>const obs = this.http.get('/doesntexist2');
  obs.finally(() =&gt; console.log('finally2'))
  obs.subscribe(() =&gt; { });
  </code></pre>
  
  <p>Both URL produce a 404.</p>
  
  <p>I run both and I only see "finally1" being displayed in the console, any idea why?</p>