title: What's the meaning of `0x0100` for a `Process::Status` value?
body: <p>I have code:</p>
  
  <pre><code>Process.spawn(RbConfig.ruby, "a ruby file", "arg")
  </code></pre>
  
  <p>and I wait and check its status by:</p>
  
  <pre><code>Process.wait
  $?.success?
  </code></pre>
  
  <p>Most of the time, it works well. But sometimes, <code>$?.success?</code> is <code>false</code> and <code>$?.to_i</code> is <code>0x0100</code>. It seems the failed process didn't get a chance to run any code before <code>0x0100</code> was returned (I didn't send any signal to the process). I wonder the meaning of <code>0x0100</code>. I further want to know if Ruby's spawn may fail when the command is all right. Could anyone help?</p>