don't fetch for unborn repositories

[shiftkey]

Fixes #2592

This currently works by checking for HEAD ref after a clone and quietly moving on, but I'm open to different approaches to tackling this if we want to make the actions here more resilient and less noisy for this error case.

Any pointers for adding new tests to catch this regression would also be welcome!

[technoweenie]

Thanks, this looks good. I added a few notes. I also wrote some bash tests for the bottom of test/test-clone.sh:

begin_test "clone empty repository"
(
  set -e

  reponame="clone_empty"
  setup_remote_repo "$reponame"

  cd "$TRASHDIR"
  git lfs clone "$GITSERVER/$reponame" "$reponame" 2>&1 | tee clone.log
  if [ "0" -ne "${PIPESTATUS[0]}" ]; then
    echo >&2 "fatal: expected clone to succeed ..."
    exit 1
  fi
)
end_test

begin_test "clone bare empty repository"
(
  set -e

  reponame="clone_bare_empty"
  setup_remote_repo "$reponame"

  cd "$TRASHDIR"
  git lfs clone "$GITSERVER/$reponame" "$reponame" --bare 2>&1 | tee clone.log
  if [ "0" -ne "${PIPESTATUS[0]}" ]; then
    echo >&2 "fatal: expected clone to succeed ..."
    exit 1
  fi
  exit 1
)
end_test

Confirmed they fail on master, and pass in this PR.

[technoweenie]

I'm not sure a message is even necessary in this case. I think it should be silently skipped if the repository is empty. The output from the wrapped git clone already tells you the repository is empty:

    Cloning into bare repository 'clone_bare_empty'...
    warning: You appear to have cloned an empty repository.

[technoweenie]

It's a common Go idiom to check for err == nil instead of ref != nil. You could even use if ref, err := git.CurrentRef(); err == nil {.

[shiftkey]

  if [ "0" -ne "${PIPESTATUS[0]}" ]; then
    echo >&2 "fatal: expected clone to succeed ..."
    exit 1
  fi
  exit 1

i see what you did there @technoweenie 😈

[shiftkey]

🍎

[technoweenie]

I guess Circle doesn't like your fork or something? We use Circle for Mac, and I can confirm this works locally, so I'm merging it.