Flushing a log file

Hi all,

Since moving to Rails 3.2.1, I haven't been able to figure out how to
flush the log file in production. I found this release note
(https://gist.github.com/1472145), which I don't understand:

It will overwrite your file. Perhaps "a" rather than "w" would append.

I also don't think it's a tunable filesystem issue...