如何使用idm工具更改管理员密码

Question

请问我尝试更改管理员密码时为什么idmtool会抱怨吗？如何解决？

python2.7 bin/idmtool --target-host http://127.0.0.1:8181 admin change-password admin@sdn
Password: 
Traceback (most recent call last):
  File "bin/idmtool", line 375, in <module>
    change_password(user, password, args.userid[0])
  File "bin/idmtool", line 248, in change_password
    existing = r.json()
  File "/usr/lib/python2.7/site-packages/requests/models.py", line 896, in json
    return complexjson.loads(self.text, **kwargs)
  File "/usr/lib64/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib64/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib64/python2.7/json/decoder.py", line 384, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded