setSize(const label)
  - When the new size is smaller than the addressed list size, the addressed
    list size is reduced and the allocated size does not change.
  - Otherwise the allocated size is adjusted, but the addressed list size
    does not change.

setSize(const label, const T&)
  - When the new size is larger than the addressed list size, both allocated
    and addressed list sizes are adjusted.

NOTE: it might be more consistent to have setSize(label) also adjust the
      addressed list size.  This also corresponds to what previous releases
      did, although I don't know if anyone has relied upon any particular
      behaviour