When using LVM, wrong partition type code is used

When MAAS is configured to use LVM for deployment, LVM physical volumes (partitions) are given the wrong partition type code -- 0x83 on MBR disks or 0FC63DAF-8483-4772-8E79-3D69D8477DE4 (8300 in gdisk) on GPT disks. These type codes are used for Linux filesystems, and indeed, some tools (like fdisk) report them as such.

The appropriate type code for LVM partitions is 0x8E (on MBR) or E6D6D379-F507-44C2-A23C-238F2A3DF928 (on GPT; 8E00 in gdisk; "lvm" flag in parted). This type code explicitly identifies LVM partitions. See, for instance:

* http://www.win.tue.nl/~aeb/partitions/partition_types-1.html
* https://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_type_GUIDs

For the most part, Linux ignores partition type codes, so the current misuse of type codes doesn't negatively affect deployment, booting, or routine operation; however, it's conceivable that some utility or script that will be run on a node will try to use type codes to identify LVM vs. Linux filesystem partitions and come to the wrong conclusion because of the incorrect type code and therefore misbehave in unpredictable ways.

MAAS version information on the server on which I discovered this issue:

$ dpkg -l '*maas*'|cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===============================-==============================-============-==================================================
ii maas 2.1.5+bzr5596-0ubuntu1~16.04.1 all "Metal as a Service" is a physical cloud and IPAM
ii maas-cert-server 0.2.30-0~74~ubuntu16.04.1 all Ubuntu certification support files for MAAS server
ii maas-cli 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS client and command-line interface
un maas-cluster-controller <none> <none> (no description available)
ii maas-common 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS server common files
ii maas-dhcp 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS DHCP server
ii maas-dns 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS DNS server
ii maas-proxy 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS Caching Proxy
ii maas-rack-controller 2.1.5+bzr5596-0ubuntu1~16.04.1 all Rack Controller for MAAS
ii maas-region-api 2.1.5+bzr5596-0ubuntu1~16.04.1 all Region controller API service for MAAS
ii maas-region-controller 2.1.5+bzr5596-0ubuntu1~16.04.1 all Region Controller for MAAS
un maas-region-controller-min <none> <none> (no description available)
un python-django-maas <none> <none> (no description available)
un python-maas-client <none> <none> (no description available)
un python-maas-provisioningserver <none> <none> (no description available)
ii python3-django-maas 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS server Django web framework (Python 3)
ii python3-maas-client 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS python API client (Python 3)
ii python3-maas-provisioningserver 2.1.5+bzr5596-0ubuntu1~16.04.1 all MAAS server provisioning libraries (Python 3)

I'm attaching the /var/log/maas directory tree from this server.