Title of Blog.BlogSheet does not get updated when updating from 6.1 to 6.x, x>1

As reported in http://xwiki.markmail.org/thread/kfdl5n5nncykuj62 the blog title is not updated when upgrading from 6.1 to a higher version (here tried with 6.2.1).

Steps to reproduce:

• unzip a xwiki-enterprise-jetty-hsqldb-6.1.zip
• start the wiki server, log in and check that the Blog.BlogSheet has $!doc.getValue("title") as title
  the full server start up is needed to populate the data directory properly and cannot be skipped when trying to reproduce. (I actually even waited until the Solr Indexer finished, which is likely not necessary).
• shut down the 6.1 server
• unzip i.e. a xwiki-enterprise-jetty-hsqldb-6.2.1.zip distro,
  and replace the "data" dir in it with a copy of the "data" dir from the 6.1 server
• start the 6.2.1-server, and upgrade via the distribution wizard
• the DW should tell you it is upgrading the blog application from 6.1 to 6.2.1
• in the log it also says

          Installing document [Home » Blog » BlogSheet]
          Done installing document [Home » Blog » BlogSheet]
  

• in the 4. step "Report" it shows that no change has been done to Blog.BlogSheet, however

After closing the DW, the page Blog.BlogSheet

• has only a version 1.1, and no version 2.1 from the update
• has a title of $!doc.getValue("title"), not of #evaluate($!doc.getValue("title"))

I unpacked the xwiki-platform-blog-ui-(number).xar in the data/extension/repository/ for both versions and the xar for has a 6.2.1 has the proper #evaluate($!doc.getValue('title')) in the Blog/BlogSheet.xml so it does not look like a tainted local maven repo.