rem: if ((group.fNumBits % fNumBits) != 0)
add: if (block * fNumBits > group.fNumBits)
context: AllocationBlock::SetTo(AllocationGroup &group, uint16 block){	// 8 blocks per byte	fNumBits = fVolume->BlockSize() << 3;	// the last group may have less bits in the last block	if ((group.fNumBits % fNumBits) != 0)		fNumBits = group.fNumBits % fNumBits;	return CachedBlock::SetTo(group.fStart + block) != NULL ? B_OK : B_ERROR;}