Fixed race condition on multiple attachment deletion

taiga/projects/attachments/api.py

@@ -74,7 +74,7 @@ class BaseAttachmentViewSet(HistoryResourceMixin, WatchedResourceMixin,
         # NOTE: When destroy an attachment, the content_object change
         #       after and not before
         self.persist_history_snapshot(obj, delete=True)
-        super().pre_delete(obj)
+        super().post_delete(obj)
 
     def get_object_for_snapshot(self, obj):
         return obj.content_object

taiga/projects/history/mixins.py

@@ -62,7 +62,7 @@ class HistoryResourceMixin(object):
             obj = self.get_object()
 
         sobj = self.get_object_for_snapshot(obj)
-        if sobj != obj and delete:
+        if sobj != obj:
             delete = False
 
         notifications_services.analize_object_for_watchers(obj, comment, user)