Content can be seen as lost if a new translation is added during a migration

If a page has been created with a given language in a monolingual wiki and a migration bring a translation on the same page for this language, this new translation page will be seen automatically in place of the existing page.
For the user his page is perceived as lost: no way to retrieve the content or the history (since he's not actually looking at the same page...).

The workaround to find back the page right now is to set the wiki to multilingual and retrieve the original page.

Original report: https://forum.xwiki.org/t/startpage-erased-without-a-trace-while-minor-lts-upgrade-10-11-3-to-10-11-8/5236