title: r2dbc - This is likely a bug leading to unpredictable outcome
body: <p>We use <code>spring-data-r2dbc:1.3.2</code> and <code>dev.miku:r2dbc-mysql:0.8.2.RELEASE</code> and experience a strange issue in production.</p>
  <p>We don't understand what is the root cause and whether it is a recoverable or can really create unpredictable outcome (as the log suggests).</p>
  <p>Periodically, we see error log as following:</p>
  <ul>
  <li>logger: dev.miku.r2dbc.mysql.client.ReactorNettyClient</li>
  <li>level: ERROR</li>
  <li>message: Exchange cancelled while exchange is active. This is likely
  a bug leading to unpredictable outcome.</li>
  </ul>
  <p>We see it a few times a day and it makes us nervous since it explicitly states: <strong>This is likely a bug leading to unpredictable outcome</strong></p>
  <p>We do not get any additional info in the log.</p>
  <p>A few questions:</p>
  <ol>
  <li>Is it really dangerous or can we consider it as a warning?</li>
  <li>How do we debug it in order to understand its cause?</li>
  <li>From the source code we could see that it assumes that exchange request cannot be cancelled if it was not completed and consider this situation as a BUG. Does it make sense? What if reactive stream was cancelled due to 'connection drop' or any other reason?</li>
  </ol>