Wikimedia Bugzilla is closed!

This happened on branch wikidata-wmfphase1beta

I created a wiki (and it created a Main page at the usual place).

Then I installed Wikibase, and set up items to be in the main namespace. When I now run maintenance/update.php it will fail with the following trace due to the Main Page being Wikitext:

MediaWiki 1.21alpha Updater

Going to run database updates for t2
Depending on the size of your database this may take a while!
Abort with control-c in the next five seconds (skip this countdown with --quick) ... 0
...wb_items_per_site doesn't exist.
...wb_items doesn't exist.
...wb_aliases doesn't exist.
...wb_texts_per_lang doesn't exist.
failed to deserialize
Backtrace:
#0 /Users/denny_WMDE/Sites/t2/extensions/Wikibase/repo/includes/content/ItemHandler.php(70): Wikibase\EntityHandler->unserializedData(''''MediaWiki ha...', 'application/jso...')
#1 /Users/denny_WMDE/Sites/t2/includes/Revision.php(979): Wikibase\ItemHandler->unserializeContent(''''MediaWiki ha...', 'application/jso...')
#2 /Users/denny_WMDE/Sites/t2/includes/Revision.php(921): Revision->getContentInternal()
#3 /Users/denny_WMDE/Sites/t2/includes/WikiPage.php(2019): Revision->getContent()
#4 /Users/denny_WMDE/Sites/t2/extensions/Wikibase/repo/includes/store/sql/SqlStore.php(101): WikiPage->doEditUpdates(Object(Revision), Object(User))
#5 /Users/denny_WMDE/Sites/t2/extensions/Wikibase/repo/includes/store/sql/SqlStore.php(130): Wikibase\SqlStore->rebuild()
#6 /Users/denny_WMDE/Sites/t2/extensions/Wikibase/repo/Wikibase.hooks.php(71): Wikibase\SqlStore->doSchemaUpdate(Object(MysqlUpdater))
#7 [internal function]: Wikibase\RepoHooks::onSchemaUpdate(Object(MysqlUpdater))
#8 /Users/denny_WMDE/Sites/t2/includes/Hooks.php(253): call_user_func_array('Wikibase\RepoHo...', Array)
#9 /Users/denny_WMDE/Sites/t2/includes/GlobalFunctions.php(3811): Hooks::run('LoadExtensionSc...', Array)
#10 /Users/denny_WMDE/Sites/t2/includes/installer/DatabaseUpdater.php(84): wfRunHooks('LoadExtensionSc...', Array)
#11 /Users/denny_WMDE/Sites/t2/includes/installer/DatabaseUpdater.php(135): DatabaseUpdater->__construct(Object(DatabaseMysql), false, Object(UpdateMediaWiki))
#12 /Users/denny_WMDE/Sites/t2/maintenance/update.php(125): DatabaseUpdater::newForDB(Object(DatabaseMysql), false, Object(UpdateMediaWiki))
#13 /Users/denny_WMDE/Sites/t2/maintenance/doMaintenance.php(110): UpdateMediaWiki->execute()
#14 /Users/denny_WMDE/Sites/t2/maintenance/update.php(156): require_once('/Users/denny_WM...')
#15 {main}