Cannot pack database

[nutjob4life]

🐛 Describe the Bug

When trying to pack the ZEO database, a stack trace occurs:

Module ZPublisher.WSGIPublisher, line 162, in transaction_pubevents
Module ZPublisher.WSGIPublisher, line 371, in publish_module
Module ZPublisher.WSGIPublisher, line 274, in publish
Module ZPublisher.mapply, line 85, in mapply
Module ZPublisher.WSGIPublisher, line 63, in call_object
Module z3c.form.form, line 233, in __call__
Module plone.z3cform.fieldsets.extensible, line 65, in update
Module plone.z3cform.patch, line 30, in GroupForm_update
Module z3c.form.group, line 145, in update
Module plone.app.z3cform.csrf, line 22, in execute
Module z3c.form.action, line 98, in execute
Module z3c.form.button, line 315, in __call__
Module z3c.form.button, line 170, in __call__
Module Products.CMFPlone.controlpanel.browser.maintenance, line 73, in handle_pack_action
Module ZODB.DB, line 838, in pack
Module ZEO.ClientStorage, line 562, in pack
Module ZEO.asyncio.client, line 764, in call
Module ZEO.asyncio.client, line 743, in call
Module ZEO.asyncio.client, line 756, in wait_for_result
Module concurrent.futures._base, line 462, in result
Module concurrent.futures._base, line 414, in __get_result
ServerException: ('exceptions.OSError', (18, 'Cross-device link'))

This is related to plone/plone.docker#40 which indicates a solution is to use ZEO_PACK_KEEP_OLD.

📜 How To Reproduce

Pack the DB TTW using root.

🔎 Expected Behavior

For it to work.