[WIP 0/8] Trying to revive GIT_TEST_PROTOCOL_VERSION

Ævar, are you planning to revive GIT_TEST_PROTOCOL_VERSION? I have updated the patchset in light of some new branches that have appeared.

This is on master merged with:
 - jk/proto-v2-hidden-refs-fix
 - tg/t5570-drop-racy-test
 - js/protocol-advertise-multi
 - jt/upload-pack-deepen-relative-proto-v2
 - jt/fetch-pack-v2

One notable change I made is that I made this envvar determine the minimum version. So, if GIT_TEST_PROTOCOL_VERSION=1 and the test explicitly states v2, v2 is used (but if GIT_TEST_PROTOCOL_VERISON=2, all use v2). I think this reduces the number of false negatives, since there are quite a few tests that use v2 specific features, and that are already marked as v2.

I included one genuine bug fix (the last patch) and the rest are either overspecifications (which I didn't investigate too deeply) or false negatives. There are still some errors when run with GIT_TEST_PROTOCOL_VERSION=2 which I don't think are false negatives - I'll continue to look into them.

Jonathan Tan (8):
  tests: define GIT_TEST_PROTOCOL_VERSION
  tests: always test fetch of unreachable with v0
  t5503: fix overspecification of trace expectation
  t5512: compensate for v0 only sending HEAD symrefs
  t5700: only run with protocol version 1
  tests: fix protocol version for overspecifications
  t5552: compensate for v2 filtering ref adv.
  remote-curl: in v2, fill credentials if needed

 protocol.c                           | 17 ++++++++--
 remote-curl.c                        |  9 +++++-
 t/README                             |  3 ++
 t/t5400-send-pack.sh                 |  2 +-
 t/t5500-fetch-pack.sh                |  4 ++-
 t/t5503-tagfollow.sh                 |  2 +-
 t/t5512-ls-remote.sh                 | 18 ++++++++---
 t/t5515-fetch-merge-logic.sh         |  4 +++
 t/t5516-fetch-push.sh                | 22 ++++++++++---
 t/t5539-fetch-http-shallow.sh        |  5 ++-
 t/t5541-http-push-smart.sh           | 14 +++++++--
 t/t5551-http-fetch-smart.sh          | 47 +++++++++++++++++++++-------
 t/t5552-skipping-fetch-negotiator.sh |  5 ++-
 t/t5700-protocol-v1.sh               |  3 ++
 t/t7406-submodule-update.sh          |  5 ++-
 15 files changed, 128 insertions(+), 32 deletions(-)