Import xml file with note (bb)F causes abort

Hi,
I noticed TPC value region in function step2tpc and Note::setTpc(int v) are not equal.
in function step2tpc:
static const int spellings[] = {
// bb b - # ##
0, 7, 14, 21, 28, // C
2, 9, 16, 23, 30, // D
4, 11, 18, 25, 32, // E
-1, 6, 13, 20, 27, // F
1, 8, 15, 22, 29, // G
3, 10, 17, 24, 31, // A
5, 12, 19, 26, 33, // B
};
values are in [-1, 33]

but in Note::setTpc(int v) :
if (v < 0 || v > 33) {
printf("Note::setTpc: bad tpc %d\n", v);
abort();
}
values are in [0, 33]

I have a note (bb)F in a file, and when I debug in Eclipse it abort here, so is this happen to be a bug?

Regards,
Fan Rui