See https://code.google.com/p/google-glog/issues/detail?id=209 - this is an updated version of that patch.

It adds a flag that allows to switch behavior from base_filename + filename_extension + time_pid_string to base_filename + filename_extension, while still defaulting to the current behavior to avoid breakage in existing code. This change would allow easier log rotation schemes and better control on what's written on disk.