ZOOKEEPER-1991 zkServer.sh returns with a zero exit status when a ZooKeeper process is already running (gsbiju via phunt)

git-svn-id: https://svn.apache.org/repos/asf/zookeeper/trunk@1733348 13f79535-47bb-0310-9956-ffa450edef68

bin/zkServer.sh

@@ -151,7 +151,7 @@ start)
     if [ -f "$ZOOPIDFILE" ]; then
       if kill -0 `cat "$ZOOPIDFILE"` > /dev/null 2>&1; then
          echo $command already running as process `cat "$ZOOPIDFILE"`.
-         exit 0
+         exit 1
       fi
     fi
     nohup "$JAVA" $ZOO_DATADIR_AUTOCREATE "-Dzookeeper.log.dir=${ZOO_LOG_DIR}" \