message: Fix recompilation test for mac
  On macs, mtime has a seconds granularity, so we need to sleep a bit
diff: @@ -298,6 +298,7 @@ fn no_rebuild_dependency() {
  p.url(),
  p.url())));
  + sleep_ms(1000);
  p.change_file("src/foo.rs", r#"
  extern crate bar;
  fn main() { bar::bar(); }
  