http://www.berklix.com/~jhs/src/bsd/fixes/FreeBSD/src/gen/etc/services.mtp.REL=CURRENT.diff
By { 12.0-ALPHA8 & 12.1-RELEASE & 2018-11-06 13.0-CURRENT } 
etc/services had moved to usr.sbin/services_mkdb/services

Not needed by 6.4

# *** 13.0-CURRENT/src/usr.sbin/services_mkdb/services	Tue Nov 25 03:59:29 2008
# --- new/src/usr.sbin/services_mkdb/services	Sun Nov 11 22:28:35 CET 2018
# ***************
# *** 107,114 ****
#   isi-gl		 55/udp	   #ISI Graphics Language
#   xns-auth	 56/tcp	   #XNS Authentication
#   xns-auth	 56/udp	   #XNS Authentication
# ! #		 57/tcp    any private terminal access
# ! #		 57/udp    any private terminal access
#   xns-mail	 58/tcp	   #XNS Mail
#   xns-mail	 58/udp	   #XNS Mail
#   #		 59/tcp	   any private file service
# --- 114,121 ----
#   isi-gl		 55/udp	   #ISI Graphics Language
#   xns-auth	 56/tcp	   #XNS Authentication
#   xns-auth	 56/udp	   #XNS Authentication
# ! # mtp		 57/tcp    any private terminal access
# ! # mtp		 57/udp    any private terminal access
#   xns-mail	 58/tcp	   #XNS Mail
#   xns-mail	 58/udp	   #XNS Mail
#   #		 59/tcp	   any private file service

*** 13.0-CURRENT/src/usr.sbin/services_mkdb/services.orig	Mon Mar 16 01:09:03 2020
--- new/src/usr.sbin/services_mkdb/services	Mon Mar 16 01:10:33 2020
***************
*** 111,118 ****
  isi-gl		 55/udp	   #ISI Graphics Language
  xns-auth	 56/tcp	   #XNS Authentication
  xns-auth	 56/udp	   #XNS Authentication
! #		 57/tcp	   any private terminal access
! #		 57/udp	   any private terminal access
  xns-mail	 58/tcp	   #XNS Mail
  xns-mail	 58/udp	   #XNS Mail
  #		 59/tcp	   any private file service
--- 111,118 ----
  isi-gl		 55/udp	   #ISI Graphics Language
  xns-auth	 56/tcp	   #XNS Authentication
  xns-auth	 56/udp	   #XNS Authentication
! # mtp		 57/tcp	   any private terminal access
! # mtp		 57/udp	   any private terminal access
  xns-mail	 58/tcp	   #XNS Mail
  xns-mail	 58/udp	   #XNS Mail
  #		 59/tcp	   any private file service