title: werid, same expression yield different value when excuting two times in irb
body: <pre><code>irb(main):051:0&gt; "ts_id &lt; what".gsub(/(=|&lt;|&gt;)\s?(\w+|\?)/,"#{$1} ?")  
  =&gt; "ts_id &gt; ?"
  irb(main):052:0&gt; "ts_id &lt; what".gsub(/(=|&lt;|&gt;)\s?(\w+|\?)/,"#{$1} ?")
  =&gt; "ts_id &lt; ?"
  </code></pre>
  
  <p>Can anyone enlighten me?</p>