message: Add Accept-Encoding request header to enable compression
diff: @@ -643,6 +643,9 @@ pub fn configure_http_handle(config: &Config, handle: &mut Easy) -> CargoResult<
  handle.useragent(&format!("cargo {}", version()))?;
  }
  + // Empty string accept encoding expands to the encodings supported by the current libcurl.
  + handle.accept_encoding("")?;
  +
  fn to_ssl_version(s: &str) -> CargoResult<SslVersion> {
  let version = match s {
  "default" => SslVersion::Default,
  