EACCES: permission denied, mkdir '/tmp/root/if-you-need-to-delete-this-open-an-issue-async-disk-cache/***'

[eauchat]

Trying to upgrade a ghost website, upgrade fails at the line mentioned in this issue title.
Ghost is installed via yunohost and the ghost_ynh package.
From my understanding, this package is creating a ghost__X user (where X is a number, so that multiple websites can be installed on the same server). I would expect therefore the async-disk-cache folder to be created in /tmp/ghost__X/ and not in /tmp/root/.
Could there be something in async-disk-cache that somehow misrecognize the user doing the action?