Change log to a warn

git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1515305 13f79535-47bb-0310-9956-ffa450edef68
Change log to a warn

git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1515306 13f79535-47bb-0310-9956-ffa450edef68