If you are in a unix envirnment, you can always:

cp log.2 log.3
cp log.1 log.2
cp log.0 log.1
cp log log.0
cat /dev/null > log
[download]

There is a slight race situation on between the cp log log.0 and the cat /dev/null where you can lose a few lines of log. This method does not require the app that is dumping to the log to close and reopen the filehandle.