Fix positional argument error when file starts with `-`

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/393553

**Problem**

We provide file path in Args list, but it does not support files that
start with dash at the beginning.

```
git ls-tree HEAD -test
error: unknown switch `e'
```

**Solution**

Provide path in PostSepArgs list.

```
git ls-tree HEAD -- -test
```

This command supports files that start with dash.

Changelog: fixed

2 files changed, 26 insertions, 3 deletions

diff --git a/internal/gitaly/service/commit/list_last_commits_for_tree.go b/internal/gitaly/service/commit/list_last_commits_for_tree.go
index e520104cb..20409fb93 100644
--- a/internal/gitaly/service/commit/list_last_commits_for_tree.go
+++ b/internal/gitaly/service/commit/list_last_commits_for_tree.go
@@ -116,9 +116,10 @@ func (s *server) newLSTreeParser(in *gitalypb.ListLastCommitsForTreeRequest, str
 
 	opts := git.ConvertGlobalOptions(in.GetGlobalOptions())
 	cmd, err := s.gitCmdFactory.New(stream.Context(), in.GetRepository(), git.Command{
-		Name:  "ls-tree",
-		Flags: []git.Option{git.Flag{Name: "-z"}, git.Flag{Name: "--full-name"}},
-		Args:  []string{in.GetRevision(), path},
+		Name:        "ls-tree",
+		Flags:       []git.Option{git.Flag{Name: "-z"}, git.Flag{Name: "--full-name"}},
+		Args:        []string{in.GetRevision()},
+		PostSepArgs: []string{path},
 	}, opts...)
 	if err != nil {
 		return nil, nil, err
diff --git a/internal/gitaly/service/commit/list_last_commits_for_tree_test.go b/internal/gitaly/service/commit/list_last_commits_for_tree_test.go
index e60b92096..f4a73f465 100644
--- a/internal/gitaly/service/commit/list_last_commits_for_tree_test.go
+++ b/internal/gitaly/service/commit/list_last_commits_for_tree_test.go
@@ -382,6 +382,28 @@ func TestSuccessfulListLastCommitsForTreeRequestWithGlobCharacters(t *testing.T)
 	})
 }
 
+func TestSuccessfulListLastCommitsForTreeRequestWithDashAtTheBeginning(t *testing.T) {
+	t.Parallel()
+
+	ctx := testhelper.Context(t)
+	cfg, repo, repoPath, client := setupCommitServiceWithRepo(t, ctx)
+
+	commitID := gittest.WriteCommit(t, cfg, repoPath, gittest.WithTreeEntries(gittest.TreeEntry{
+		Path: "-test", Mode: "040000", OID: gittest.WriteTree(t, cfg, repoPath, []gittest.TreeEntry{
+			{Path: "README.md", Mode: "100644", Content: "something"},
+		}),
+	}))
+
+	stream, err := client.ListLastCommitsForTree(ctx, &gitalypb.ListLastCommitsForTreeRequest{
+		Repository: repo,
+		Revision:   commitID.String(),
+		Path:       []byte("-test"),
+		Limit:      100,
+	})
+	require.NoError(t, err)
+	require.Equal(t, []string{"-test"}, fetchCommitPaths(t, stream))
+}
+
 func fileExistsInCommits(t *testing.T, stream gitalypb.CommitService_ListLastCommitsForTreeClient, path string) bool {
 	t.Helper()