Fixed #19807 -- Sanitized getpass input in createsuperuser

Python 2 getpass on Windows doesn't accept unicode, even when
containing only ascii chars.
Thanks Semmel for the report and tests.

django/contrib/auth/management/commands/createsuperuser.py

@@ -122,7 +122,7 @@ class Command(BaseCommand):
                 while password is None:
                     if not password:
                         password = getpass.getpass()
-                        password2 = getpass.getpass('Password (again): ')
+                        password2 = getpass.getpass(force_str('Password (again): '))
                         if password != password2:
                             self.stderr.write("Error: Your passwords didn't match.")
                             password = None

django/contrib/auth/tests/basic.py

@@ -13,7 +13,7 @@ from django.core.management import call_command
 from django.test import TestCase
 from django.test.utils import override_settings
 from django.utils.encoding import force_str
-from django.utils.six import StringIO
+from django.utils.six import binary_type, StringIO
 
 
 def mock_inputs(inputs):
@@ -24,8 +24,11 @@ def mock_inputs(inputs):
     def inner(test_func):
         def wrapped(*args):
             class mock_getpass:
-                pass
-            mock_getpass.getpass = staticmethod(lambda p=None: inputs['password'])
+                @staticmethod
+                def getpass(prompt=b'Password: ', stream=None):
+                    # getpass on Windows only supports prompt as bytestring (#19807)
+                    assert isinstance(prompt, binary_type)
+                    return inputs['password']
 
             def mock_input(prompt):
                 # prompt should be encoded in Python 2. This line will raise an