Comment 4 for bug 420903

"preseed --owner d-i", not "d-i --owner partman" ...

However, please start without any attempts to modify partman's behaviour using the 'preseed' command at all. I'd like to see the behaviour with a clean slate, just Kickstart's native behaviour with the 'clearpart' and 'part' commands you have. Partitioning in Kickstart is not intended to require the use of the 'preseed' command for reasonably straightforward cases.