Fixing django 2.1 probs in student management commands (#23587)

* Requiring at least one args in a mutually exclusive group to be set

bulk_change_enrollment requires one of agrs: org or course to be set
for it to function correctly.

* Creating new function to verify initial password hash

Starting with django 2.1, the function is_password_usable no longer checks whether encode
is a valid password created by a django hasher(hasher in  PASSWORD_HASHERS setting)

Adding this function to create constant behavior as we upgrade django versions

common/djangoapps/student/management/commands/bulk_change_enrollment.py

@@ -36,7 +36,7 @@ class Command(BaseCommand):
     """
 
     def add_arguments(self, parser):
-        group = parser.add_mutually_exclusive_group()
+        group = parser.add_mutually_exclusive_group(required=True)
         group.add_argument(
             '-c', '--course',
             help='The course to change enrollments in')
@@ -64,7 +64,6 @@ class Command(BaseCommand):
         to_mode = options['to_mode']
         commit = options['commit']
         course_keys = []
-
         if course_id:
             try:
                 course_key = CourseKey.from_string(course_id)

common/djangoapps/student/management/commands/manage_user.py

@@ -5,7 +5,7 @@ Django users, set/unset permission bits, and associate groups by name.
 
 
 from django.contrib.auth import get_user_model
-from django.contrib.auth.hashers import is_password_usable
+from django.contrib.auth.hashers import is_password_usable, identify_hasher
 from django.contrib.auth.models import Group
 from django.core.management.base import BaseCommand, CommandError
 from django.db import transaction
@@ -15,6 +15,20 @@ from openedx.core.djangoapps.user_authn.utils import generate_password
 from student.models import UserProfile
 
 
+def is_valid_django_hash(encoded):
+    """
+    Starting with django 2.1, the function is_password_usable no longer checks whether encode
+    is a valid password created by a django hasher (hasher in  PASSWORD_HASHERS setting)
+
+    Adding this function to create constant behavior as we upgrade django versions
+    """
+    try:
+        identify_hasher(encoded)
+    except ValueError:
+        return False
+    return True
+
+
 class Command(BaseCommand):
     # pylint: disable=missing-docstring
 
@@ -87,7 +101,7 @@ class Command(BaseCommand):
 
         if created:
             if initial_password_hash:
-                if not is_password_usable(initial_password_hash):
+                if not (is_password_usable(initial_password_hash) and is_valid_django_hash(initial_password_hash)):
                     raise CommandError('The password hash provided for user {} is invalid.'.format(username))
                 user.password = initial_password_hash
             else: