message: reacto.for_each: Shorten threads name.
diff: @@ -35,7 +35,7 @@ namespace elle
  std::reference_wrapper<std::remove_reference_t<decltype(elt)>>,
  decltype(elt)>;
  scope.run_background(
  - elle::print("{}: {}: {}",
  + elle::print("{}: {}: %f",
  reactor::scheduler().current()->name(),
  name.empty() ? "for-each" : name,
  elt),
  