Log Message: ----------- Change ps_status.c to explicitly track the current logical length of ps_buffer. This saves cycles in get_ps_display() on many popular platforms, and more importantly ensures that get_ps_display() will correctly return an empty string if init_ps_display() hasn't been called yet. Per trouble report from Ray Stell, in which log_line_prefix %i produced junk early in backend startup.
Back-patch to 8.0. 7.4 doesn't have %i and its version of get_ps_display() makes no pretense of avoiding pad junk anyhow.