I confirm that this workaround works. Go back in the install interface, log as root in a terminal window, delete the partition with fdisk, recreate it (still in fdisk... at least that's what I did), and proceed with the installer reusing existing partitions.
Michael. -- mount points preparation locked - "No root file system" https://launchpad.net/bugs/67130 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs