Merge branch 'es/some-up-to-date-messages-must-stay'

Comment updates to help developers not to attempt to modify
messages from plumbing commands that must stay constant.

It might make sense to reassess the plumbing needs every few years,
but that should be done as a separate effort.

* es/some-up-to-date-messages-must-stay:
  messages: mark some strings with "up-to-date" not to touch

diff --cc builtin/send-pack.c
Simple merge

diff --cc http-push.c
Simple merge

diff --cc transport.c
Simple merge