vector::times panics on empty vector

[VladimirMarkelov]

  let vv1: Vec<i32> = Vec::new();
  let vv2: Vec<i32> = Vec::new();
  assert_eq!(vv1.times(4), vv2);

thread 'it_multiplies' panicked at 'index out of bounds: the len is 0 but the index is 0', src\libcollections\vec.rs:1422