title: Robot Framework: How to merge old/new statuses using rebot --merge and keep the only one?
body: <p>I'm using <strong>rebot</strong> tool to merge outputs after re-execution of failed tests.</p>
  
  <pre><code>robot --output original.xml /path/to/dir/.
  robot --rerunfailed original.xml --output rerun.xml /path/to/dir/.
  rebot -o machine1.xml -l machine1.html --merge original.xml rerun.xml
  </code></pre>
  
  <p>The same action is provided on few test machines.
  Test suite is identical and is executed against each VM. All VMs are considered as identical, however, they are not stable and I receive different results on each machine.
  I want to merge all results from all machines and retrieve the maximum number of Passed tests, to understand whether the test is REALLY failing or it's just unstable environment and test is OK by itself.</p>
  
  <p>Other words, if test passed at least on 1 machine, but failed on other 3 machines, it needs to be considered as Passed in the final report. </p>
  
  <p>However I receive False for such case.</p>
  
  <p>Is it possible to change the behavior somehow?</p>
  
  <p>Example from the final report:</p>
  
  <pre><code>Status: FAIL (critical)
  Message:    Re-executed test has been merged.
  New status: FAIL
  New message: Re-executed test has been merged.
  New status: FAIL
  New message: IndexError: Given index 0 is out of the range 0--1.
  Old status: FAIL
  Old message: IndexError: Given index 0 is out of the range 0--1.
  Old status: PASS
  Old message: Re-executed test has been merged.
  New status: PASS
  New message: 
  Old status: PASS
  Old message: Re-executed test has been merged.
  New status: PASS
  New message: 
  Old status: PASS
  Old message: 
  </code></pre>