Move select_for_update into transaction block

Author: naglepuff

dandiapi/api/views/dandiset.py

@@ -485,7 +485,7 @@ def unembargo(self, request, dandiset__pk):
     # TODO: move these into a viewset
     @action(methods=['GET', 'PUT'], detail=True)
     def users(self, request, dandiset__pk):  # noqa: C901
-        dandiset: Dandiset = Dandiset.objects.select_for_update().get(pk=dandiset__pk)
+        dandiset: Dandiset = self.get_object()
         if request.method == 'PUT':
             if dandiset.unembargo_in_progress:
                 raise DandisetUnembargoInProgressError
@@ -522,13 +522,14 @@ def users(self, request, dandiset__pk):  # noqa: C901
 
             # All owners found
             with transaction.atomic():
+                dandiset_locked = Dandiset.objects.select_for_update().get(pk=dandiset__pk)
                 owners = user_owners + [acc.user for acc in socialaccount_owners]
-                removed_owners, added_owners = replace_dandiset_owners(dandiset, owners)
-                dandiset.save()
+                removed_owners, added_owners = replace_dandiset_owners(dandiset_locked, owners)
+                dandiset_locked.save()
 
                 if removed_owners or added_owners:
                     audit.change_owners(
-                        dandiset=dandiset,
+                        dandiset=dandiset_locked,
                         user=request.user,
                         removed_owners=removed_owners,
                         added_owners=added_owners,