message: Add a way to skip the `use_the_cli` test for rust repo.
diff: use git2;
  +use std::env;
  use std::fs::{self, File};
  use std::io::prelude::*;
  use std::net::{TcpListener, TcpStream};
  @@ -2575,6 +2576,12 @@ fn failed_submodule_checkout() {
  #[test]
  fn use_the_cli() {
  + if env::var("CARGO_TEST_DISABLE_GIT_CLI") == Ok("1".to_string()) {
  + // mingw git on Windows does not support Windows-style file URIs.
  + // Appveyor in the rust repo has that git up front in the PATH instead
  + // of Git-for-Windows, which causes this to fail.
  + return;
  + }
  let project = project();
  let git_project = git::new("dep1", |project| {
  project
  