[Bug] Local clone fails reporing an empty checkout as not empty

Biên dịch repro.c bằng lệnh pkg-config được nêu, chuẩn bị các repository tạm thời và cấu hình, rồi chạy tái hiện clone cục bộ. Theo dõi đường dẫn clone cục bộ từ chối bare repository đã có nội dung, sau đó xác minh rằng việc clone thành công với thiết lập này và thêm coverage cho trường hợp được báo cáo.

This error is really weird, so I’d like to start by apologizing for the odd title of this issue :(.

TL;DR libgit2 reports git_clone failed: the repository is not empty on a empty repository.

How to reproduce

First we need a helper binary using libgit2.

// repro.c
#include <git2.h>
#include <stdio.h>
#include <string.h>

static int fail(const char *what, int code) {
  const git_error *error = git_error_last();
  fprintf(stderr, "%s failed", what);
  if (error != NULL && error->message != NULL) {
    fprintf(stderr, ": %s", error->message);
  } else {
    fprintf(stderr, " with code %d", code);
  }
  fputc('\n', stderr);
  return 1;
}

static int usage(void) {
  fprintf(stderr, "usage:\n"
                  "  libgit2-repro init-bare <repo>\n"
                  "  libgit2-repro clone-local <src> <dst>\n");
  return 2;
}

int main(int argc, char **argv) {
  int status = 0;

  git_libgit2_init();

  if (argc == 3 && strcmp(argv[1], "init-bare") == 0) {
    git_repository *repo = NULL;
    git_repository_init_options opts;
    int rc = git_repository_init_init_options(
        &opts, GIT_REPOSITORY_INIT_OPTIONS_VERSION);
    if (rc != 0) {
      status = fail("git_repository_init_init_options", rc);
      goto done;
    }
    opts.flags = GIT_REPOSITORY_INIT_BARE | GIT_REPOSITORY_INIT_MKPATH;
    rc = git_repository_init_ext(&repo, argv[2], &opts);
    if (rc != 0) {
      status = fail("git_repository_init_ext", rc);
      goto done;
    }
    git_repository_free(repo);
  } else if (argc == 4 && strcmp(argv[1], "clone-local") == 0) {
    git_repository *repo = NULL;
    git_clone_options opts;
    int rc = git_clone_options_init(&opts, GIT_CLONE_OPTIONS_VERSION);
    if (rc != 0) {
      status = fail("git_clone_options_init", rc);
      goto done;
    }
    opts.local = GIT_CLONE_LOCAL;
    opts.checkout_opts.checkout_strategy = GIT_CHECKOUT_DRY_RUN;
    rc = git_clone(&repo, argv[2], argv[3], &opts);
    if (rc != 0) {
      status = fail("git_clone", rc);
      goto done;
    }
    git_repository_free(repo);
  } else {
    status = usage();
  }

done:
  git_libgit2_shutdown();
  return status;
}

You could compile it by:

cc -std=c11 $(pkg-config --cflags libgit2) -o libgit2-repro repro.c $(pkg-config --libs libgit2)

Then, initialize the environment:

work="$(mktemp -d /tmp/repro-XXXXXX)"
mkdir "$work/home"
export HOME="$work/home" # create a fake home so that this would not break your env :)
export GIT_CONFIG_NOSYSTEM=1

And the following two files:

// $HOME/.gitconfig
[includeIf "gitdir:/"]
    path = ~/other.gitconfig

// $HOME/other.gitconfig
[init]
    defaultBranch = main
[user]
    email = test@example.com
    name = test

Then, we could create the repositories:

$ git init "$work/src"
$ printf "hello\n" > "$work/src/README.md"
$ git -C "$work/src" add README.md
$ git -C "$work/src" commit -m initial
[main (root-commit) b80a053] initial
 1 file changed, 1 insertion(+)
 create mode 100644 README.md
$ cat "$work/src/.git/HEAD"
ref: refs/heads/main
$ ./libgit2-repro init-bare "$work/db.git"
$ cat "$work/db.git/HEAD"
ref: refs/heads/master
$ git --git-dir="$work/db.git" fetch "$work/src" '+refs/heads/*:refs/remotes/origin/*' '+HEAD:refs/remotes/origin/HEAD'
remote: Enumerating objects: 3, done.
remote: Counting objects: 100% (3/3), done.
remote: Total 3 (delta 0), reused 0 (delta 0), pack-reused 0 (from 0)
Unpacking objects: 100% (3/3), 187 bytes | 187.00 KiB/s, done.
From tmp/src
 * [new branch]      main       -> origin/main
 * [new ref]         HEAD       -> origin/HEAD
$ ./libgit2-repro clone-local "$work/db.git" "$work/checkout"
git_clone failed: the repository is not empty