The GPL license states that "THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION". So whether it is "safe" or not, is up to the user :)
In my case, I'm using the branch in a production environment. Note it doesn't just have bugfixes but also some code changes which I consider improvements.