#ifdef PERL_COPY_ON_WRITE
/* The match may make the string COW. If so, brilliant, because that's
   just saved us one malloc, copy and free - the regexp has donated
   the old buffer, and we malloc an entirely new one, rather than the
   regexp malloc()ing a buffer and copying our original, only for
   us to throw it away here during the substitution.  */
if (SvIsCOW(TARG)) {
    sv_force_normal_flags(TARG, SV_COW_DROP_PV);
} else
#endif