bin/50590: gpt migrate fails on extended MBR partitions

[martin%NetBSD.org@localhost]

>Number:         50590
>Category:       bin
>Synopsis:       gpt migrate fails on extended MBR partitions
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 25 10:55:00 +0000 2015
>Originator:     Martin Husemann
>Release:        NetBSD 7.99.25
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 7.99.25 NetBSD 7.99.25 (NIGHT-OWL) #367: Mon Dec 21 16:32:08 CET 2015 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:

Given a disk with MBR like this:

[/tmp] root@night-owl # fdisk vnd0
Disk: /dev/rvnd0d
NetBSD disklabel disk geometry:
cylinders: 3145728, heads: 64, sectors/track: 32 (2048 sectors/cylinder)
total sectors: 4294967295, bytes/sector: 512

BIOS disk geometry:
cylinders: 1024, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 4294967295

Partitions aligned to 2048 sector boundaries, offset 2048

Partition table:
0: Extended partition (sysid 5)
    bootmenu: DOS Ext
    start 2048, size 409600 (200 MB, Cyls 0-25/159/6)
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Extended partition table:
E0: <UNUSED>
E1: Primary 'big' DOS, 16-bit FAT (> 32MB) (sysid 6)
    bootmenu: Legacy
    start 6144, size 405504 (198 MB, Cyls 0/65/2-25/159/6)
        PBR is not bootable: All bytes are identical (0x00)
Bootselector enabled, timeout 10 seconds.
No active partition.
Drive serial number: 0 (0x00000000)

(which was created for testing by NetBSD's fdisk -u command and a few obvious
from above output menu choices), trying to convert this to a GPT labeled
disk fails:

[/tmp] root@night-owl # gpt migrate vnd0
gpt: /dev/rvnd0d: unknown partition type (5)


>How-To-Repeat:
s/a

>Fix:
n/a