TCP ssthresh in Linux/RFC

The Linux set ssthresh upon entering recovery stage (tcp_fastretrans_alert()) to
1) max(snd_cwnd/2, 2) in tcp_cong.c
2) max((tp->snd_cwnd * beta) / BICTCP_BETA_SCALE, 2U) in tcp_cubic.c

but RFC 5681 says  ssthresh = max (FlightSize / 2, 2*SMSS). It also
specifically mentions
" Implementation Note: An easy mistake to make is to simply use cwnd,
   rather than FlightSize, which in some implementations may
   incidentally increase well beyond rwnd."

I can think of a few pros and cons of both design, but would like to
hear Linux developers opinions first.

Yuchung