message: Allow registry option for cargo install.
diff: @@ -34,6 +34,7 @@ pub fn cli() -> App {
  )
  .arg_target_triple("Build for the target triple")
  .arg(opt("root", "Directory to install packages into").value_name("DIR"))
  + .arg(opt("registry", "Registry to use").value_name("REGISTRY"))
  .after_help(
  "\
  This command manages Cargo's local set of installed binary crates. Only packages
  @@ -102,6 +103,8 @@ pub fn exec(config: &mut Config, args: &ArgMatches) -> CliResult {
  } else if krates.is_empty() {
  from_cwd = true;
  SourceId::for_path(config.cwd())?
  + } else if let Some(registry) = args.value_of("registry") {
  + SourceId::alt_registry(config, registry)?
  } else {
  SourceId::crates_io(config)?
  };
  