message: Simplify array filter assignment
diff: @@ -218,11 +218,10 @@ impl VariableStore for Shell {
  Ok(VariableType::Array(values)) => {
  match self.variables.get_mut(key.name) {
  Some(VariableType::Array(ref mut array)) => {
  - let mut iterator: Box<Iterator<Item=&types::Str>> = Box::new(array.iter());
  - for value in &values {
  - iterator = Box::new(iterator.filter(move |item| *item != value));
  - }
  - *array = iterator.cloned().collect();
  + *array = array.iter()
  + .filter(|item| values.iter().all(|value| *item != value))
  + .cloned()
  + .collect();
  }
  None => {
  eprintln!("ion: assignment error: {}: cannot head concatenate non-array variable", key.name);
  