Fix LDAP auth for new users. (#192)

cvat/apps/authentication/auth_ldap.py

@@ -25,5 +25,9 @@ def create_user(sender, user=None, ldap_user=None, **kwargs):
                 if role == AUTH_ROLE.ADMIN:
                     user.is_staff = user.is_superuser = True
 
-    user.groups.set(user_groups)
+    # It is important to save the user before adding groups. Please read
+    # https://django-auth-ldap.readthedocs.io/en/latest/users.html#populating-users
+    # The user instance will be saved automatically after the signal handler
+    # is run.
     user.save()
+    user.groups.set(user_groups)