Ubiquity pops out a warning message from partman-partitioning on UEFI BIOS when there is a EFI system partition existed.

The message is from partman-partitioning/no_bootable_gpt_efi of lp:~ubuntu-core-dev/partman-partitioning/ubuntu.
It seems relative to http://bazaar.launchpad.net/~ubuntu-core-dev/partman-partitioning/ubuntu/revision/913 .

This seems to be a regression of Bug #855871.

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I can see what you're trying to do with this patch, but I think it's a workaround for the real problem, which is that the EFI partition isn't being detected. I'd prefer to fix that instead. Doing so would probably also fix bug 900245.

In the case of GPT partition tables, we can reliably detect existing EFI System Partitions using something like this:

  [ "$(blkid -o value -s PART_ENTRY_TYPE "$path")" = c12a7328-f81f-11d2-ba4b-00a0c93ec93b ]

This bug was fixed in the package partman-efi - 25ubuntu1

---------------
partman-efi (25ubuntu1) precise; urgency=low

  * Resynchronise with Debian. Remaining changes:
    - Automatically use existing EFI system partitions on Intel Macs as EFI
      boot partitions.
    - Create fat32 EFI partitions with the name "EFI System Partition" by
      default on Intel Macs.
    - choose_method/efi/do_option: Make sure no mountpoint is set.
    - Remove efi-modules dependency; it seems to be built into Ubuntu
      kernels now.
    - Require partman-base >= 129 to support a null value for the name.
    - Automatically mount the first method=efi filesystem we see on
      /boot/efi.
    - On x86 architectures, create EFI system partitions using FAT32 rather
      than FAT16, and require newly-created ones to have a minimum size of
      34091008 bytes.
    - Never format EFI system partitions that already contain a filesystem.
  * Detect existing EFI system partitions more reliably on GPT partition
    tables (LP: #972122, #900245).

partman-efi (25) unstable; urgency=low

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