This is not an XWiki Standard bug IMO,
I'm not sure, what we do right now has little interest and we might want to change it. We'll still need to provide fake exo pages for past XWiki versions but we may want to do change the mechanism. To be decided. See https://jira.xwiki.org/browse/XINFRA-417?focusedId=118012&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-118012
