XWikiPreferences vanish on newly created subwikis

Steps to reproduce:

• download and unpack http://maven.xwiki.org/releases/org/xwiki/platform/xwiki-platform-distribution-jetty-hsqldb/14.2/xwiki-platform-distribution-jetty-hsqldb-14.2.zip
• start jetty and go trough the DW
• after running the DW go to the wiki manager, create a new subwiki (local users only)
• visit the new subwiki
• go to the wiki admin in that subwiki

Expected:

Subwiki administration should appear

Actual:

• an empty page is displayed
• returning to the home page of the subwiki shows this in some default fallback layout
• the XWiki.XWikiPreferences page has only a version 1.1, without an associated XWikiPreferences object
• after restartign jetty, the admin is back, but with an empty XWikiPreferences object
• rolling it back to the version coming from "Base Flavor Application 14.2" results in  the message that the page has been deleted.