title: How to preserve rx Scheduler without getting it as a method parameter?
body: <p>If I do something like this:</p>
  
  <pre><code>Observable.just(1)
  .flatMap(
      //inner chain
      Observable.just(2)
          .subscribeOn(Schedulers.newThread())
  )
  .map(// we are in the inner chain thread! //)
  .subscribeOn(Schedulers.newThread())
  .subscribe()
  </code></pre>
  
  <p>then inner thread will "leak" to the main observable chain.
  How to preserve original thread?</p>
  
  <p>Thanks in advance!</p>