plink2 pgenlib.PgenWriter caused a segmentation fault

pgen_write.out.txt

$ python pgen_write.py
2017-07-04 00:44:50,706 pgen_write   DEBUG    pgen write test script
2017-07-04 00:44:50,706 read_alleles_range DEBUG    reading alleles range 0:10 from ./pgen_in.pgen
2017-07-04 00:44:50,725 read_alleles_range DEBUG    The shape of the numpy nd-array is (10, 224676)
2017-07-04 00:44:50,725 pgen_write   DEBUG    shape of buffer is (10, 224676)
2017-07-04 00:44:50,727 pgen_write   DEBUG    writing SNP 0 of 10 ...
2017-07-04 00:44:50,728 pgen_write   DEBUG    writing SNP 1 of 10 ...
2017-07-04 00:44:50,730 pgen_write   DEBUG    writing SNP 2 of 10 ...
2017-07-04 00:44:50,731 pgen_write   DEBUG    writing SNP 3 of 10 ...
2017-07-04 00:44:50,733 pgen_write   DEBUG    writing SNP 4 of 10 ...
2017-07-04 00:44:50,734 pgen_write   DEBUG    writing SNP 5 of 10 ...
2017-07-04 00:44:50,736 pgen_write   DEBUG    writing SNP 6 of 10 ...
2017-07-04 00:44:50,737 pgen_write   DEBUG    writing SNP 7 of 10 ...
Segmentation fault

pgen_write.py

from __future__ import print_function

import sys
import os
import logging
from logging.config import dictConfig
import numpy as np
import collections as cl

import pgenlib as pg

logging_config = dict(
    version = 1,
    formatters = {
        'f': {'format':
              '%(asctime)s %(name)-12s %(levelname)-8s %(message)s'}
        },
    handlers = {
        'h': {'class': 'logging.StreamHandler',
              'formatter': 'f',
              'level': logging.DEBUG}
        },
    root = {
        'handlers': ['h'],
        'level': logging.DEBUG,
        },
)
dictConfig(logging_config)

def read_alleles_range(pgen_f, rangeStart, rangeEnd):
    logger_read_alleles_range = logging.getLogger('read_alleles_range')    
    logger_read_alleles_range.debug(
        'reading alleles range {}:{} from {}'.format(rangeStart, rangeEnd, pgen_f)
    )            
    with pg.PgenReader(pgen_f) as pgr:
        buffer = np.zeros((rangeEnd - rangeStart, pgr.get_raw_sample_ct() * 2), dtype=np.int32)
        pgr.read_alleles_range(rangeStart, rangeEnd, buffer)
    logger_read_alleles_range.debug(
        'The shape of the numpy nd-array is {}'.format(buffer.shape)
    )                    
    return buffer

def pgen_write(pgen_in, pgen_out, rangeStart, rangeEnd):
    logger_pgen_write = logging.getLogger('pgen_write')
    logger_pgen_write.debug(
        'pgen write test script'
    )
    buf = read_alleles_range(pgen_in, rangeStart, rangeEnd)
    logger_pgen_write.debug(
        'shape of buffer is {}'.format(buf.shape)
    )
    with pg.PgenWriter(pgen_out, buf.shape[1] / 2, buf.shape[0], True) as pgw:
	for snp_pos in range(rangeEnd - rangeStart):
            logger_pgen_write.debug('writing SNP {} of {} ...'.format(snp_pos, rangeEnd-rangeStart))
            pgw.append_alleles(buf[snp_pos])
        # pgw.append_alleles_batch(buf)
	# this append_alleles_batch does not work either

def main():
    pgen_in  = './pgen_in.pgen'
    pgen_out = './pgen_out.pgen'
    pgen_write(pgen_in, pgen_out, rangeStart = 0, rangeEnd = 10)

if __name__ == '__main__' :
    main()