LDAP authentication with incorrect password causes a 500

[Cryptophobia]

From @hankjacobs on June 7, 2017 19:48

I recently upgraded from 2.13.0 to 2.15.0. After upgrading, deis login with a valid LDAP user but an incorrect password started to fail with Error: Internal Server Error.

The following stack trace appears in the deis-controller logs:

ERROR:root:Uncaught Exception
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/ldap/ldapobject.py", line 265, in _ldap_call
    result = func(*args,**kwargs)
ldap.INVALID_CREDENTIALS: {'desc': 'Invalid credentials'}

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/rest_framework/views.py", line 486, in dispatch
    response = handler(request, *args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/rest_framework/authtoken/views.py", line 17, in post
    serializer.is_valid(raise_exception=True)
  File "/usr/local/lib/python3.5/dist-packages/rest_framework/serializers.py", line 237, in is_valid
    self._validated_data = self.run_validation(self.initial_data)
  File "/usr/local/lib/python3.5/dist-packages/rest_framework/serializers.py", line 435, in run_validation
    value = self.validate(value)
  File "/usr/local/lib/python3.5/dist-packages/rest_framework/authtoken/serializers.py", line 16, in validate
    user = authenticate(username=username, password=password)
  File "/usr/local/lib/python3.5/dist-packages/django/contrib/auth/__init__.py", line 100, in authenticate
    user = backend.authenticate(*args, **credentials)
  File "/usr/local/lib/python3.5/dist-packages/django_auth_ldap/backend.py", line 171, in authenticate
    user = ldap_user.authenticate(password)
  File "/usr/local/lib/python3.5/dist-packages/django_auth_ldap/backend.py", line 344, in authenticate
    self._authenticate_user_dn(password)
  File "/usr/local/lib/python3.5/dist-packages/django_auth_ldap/backend.py", line 460, in _authenticate_user_dn
    self._bind_as(self.dn, password, sticky=sticky)
  File "/usr/local/lib/python3.5/dist-packages/django_auth_ldap/backend.py", line 765, in _bind_as
    force_str(bind_password))
  File "/usr/local/lib/python3.5/dist-packages/ldap/ldapobject.py", line 386, in simple_bind_s
    resp_type, resp_data, resp_msgid, resp_ctrls = self.result3(msgid,all=1,timeout=self.timeout)
  File "/usr/local/lib/python3.5/dist-packages/ldap/ldapobject.py", line 682, in result3
    resp_ctrl_classes=resp_ctrl_classes
  File "/usr/local/lib/python3.5/dist-packages/ldap/ldapobject.py", line 689, in result4
    ldap_result = self._ldap_call(self._l.result4,msgid,all,timeout,add_ctrls,add_intermediates,add_extop)
  File "/usr/local/lib/python3.5/dist-packages/ldap/ldapobject.py", line 273, in _ldap_call
    e.args[0]['info'] = strerror(e.args[0]['errno'])
KeyError: 'errno'
10.68.167.81 "POST /v2/auth/login/ HTTP/1.1" 500 25 "Deis Client v2.15.0"

Copied from original issue: deis/controller#1307