Redirecting python's stdout to the file fails

问题:

I have a python script that connects to the Twitter Firehose and sends data downstream for processing. Before it was working fine, but now I'm trying to get only text body. (It's not a question about how I should extract data from Twitter or how do encode/decode ascii characters). So when I launch my script directly like this:

python -u fetch_script.py

It works just fine, and I can see messages are coming to the screen. For example:

root@domU-xx-xx-xx-xx:/usr/local/streaming# python -u fetch_script.py 
Cuz I'm checking you out >on Facebook<
RT @SearchlightNV: #BarryLies