message: Update a test to not clone the real index
  A local index should work ok!
diff: @@ -2,6 +2,8 @@ use std::fs::{self, File};
  use std::io::prelude::*;
  use cargotest::support::{project, execs};
  +use cargotest::support::registry::Package;
  +use cargotest::ChannelChanger;
  use hamcrest::{assert_that, existing_file, is_not};
  #[test]
  @@ -73,7 +75,8 @@ fn adding_and_removing_packages() {
  #[test]
  fn no_index_update() {
  - use cargotest::ChannelChanger;
  + Package::new("serde", "1.0.0").publish();
  +
  let p = project("foo")
  .file("Cargo.toml", r#"
  [package]
  @@ -88,12 +91,12 @@ fn no_index_update() {
  .build();
  assert_that(p.cargo("generate-lockfile"),
  - execs().with_stdout("")
  - .with_stderr_contains(" Updating registry `https://github.com/rust-lang/crates.io-index`"));
  + execs().with_stderr("\
  +[UPDATING] registry `[..]`
  +"));
  assert_that(p.cargo("generate-lockfile").masquerade_as_nightly_cargo().arg("-Zno-index-update"),
  - execs().with_status(0).with_stdout("")
  - .with_stderr_does_not_contain(" Updating registry `https://github.com/rust-lang/crates.io-index`"));
  + execs().with_status(0).with_stdout("").with_stderr(""));
  }
  #[test]
  