Actually, I removed the previous patch, which doesn't offer anything (content of /etc/system-release and /etc/redhat-release are identical on Scientific Linux, and RedHat). So we only detect Redhat, and if it is a RedHat, then we look for the content of the file. If it contain Scientific, it is a Scientifc linux.
This is more compliant with the way the system is build (it looks like a RedHat, but when we drill down the files, it is indeed a Scientific Linux)