title: java negative lookbehind regex bug?
body: <p>My java @windows is:</p>
  
  <pre><code>java version "1.6.0_29"
  Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
  Java HotSpot(TM) Client VM (build 20.4-b02, mixed mode, sharing)
  </code></pre>
  
  <p>Code</p>
  
  <pre><code>Pattern.compile(".+(?&lt;!(xxx|idea|perforator|pycharm|s).*)").matcher("xxx").matches() //returns TRUE while it should return FALSE
  Pattern.compile(".+(?&lt;!(xxx|idea|perforator|pycharm|s).*)").matcher("perforator").matches() //returns FALSE
  </code></pre>
  
  <p>Looks like negative lookbehind fails if string is smaller than 8 chars.</p>
  
  <p>Is it bug or do I misunderstand something about regex?</p>