Exception in thread "Robot-20090731141956043-4" java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at org.seasar.robot.filter.impl.UrlFilterImpl.match(UrlFilterImpl.java:51)
at org.seasar.robot.S2RobotThread.isValid(S2RobotThread.java:320)
at org.seasar.robot.S2RobotThread.run(S2RobotThread.java:117)
at java.lang.Thread.run(Thread.java:619)
robots.txt の読み込みタイミングによって、発生する。