Debian packages don't give xwiki mysql user necessary privileges for creating sub-wikis

An installation form Debian packages doesn't give the mysql XWiki user the necessary rights to create new wikis. Trying to create one results in "com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Access denied for user 'xwiki'@'localhost' to database ‘XXX' ". This can probably be fixed by manually adapting user rights, but users expect Debian packages to "just work" and think that the platform is broken. This should be fixed in the debian post-installation scripts.