Undefined new-abi symbol untranslated by c++filt

[Chip Salzenberg]

This symbol comes up undefined when bootstrapping with -fnew-abi:

  _ZSt26__uninitialized_fill_n_auxIPSbIcSt11char_traitsIcESaIcEEjSsET_S5_T0_RKT1_5_BoolILb0EE

Unfortunately, 'c++filt -s new-gnu-abi' can't decode it.  Help?
-- 
Chip Salzenberg              - a.k.a. -              <chip@valinux.com>
"I wanted to play hopscotch with the impenetrable mystery of existence,
    but he stepped in a wormhole and had to go in early."  // MST3K