oem-setup misconfigures locale if install and user language differ

Image: Desktop amd64 final Yakkety release candidate
Mode: OEM, selected "German" in gfxboot, no network

The install (in German) went fine, and oem-setup started in German. I selected French as my user's language, but this ends up in a weird locale mix. Right after oem-setup, the desktop appears in German (sorry, I don't have "locale" output any more), and after a reboot it appears in English.

$ locale
LANG=fr_FR.UTF-8
LANGUAGE=fr_FR
LC_CTYPE="fr_FR.UTF-8"
LC_NUMERIC=de_DE.UTF-8
LC_TIME=de_DE.UTF-8
LC_COLLATE="fr_FR.UTF-8"
LC_MONETARY=de_DE.UTF-8
LC_MESSAGES="fr_FR.UTF-8"
LC_PAPER=de_DE.UTF-8
LC_NAME=de_DE.UTF-8
LC_ADDRESS=de_DE.UTF-8
LC_TELEPHONE=de_DE.UTF-8
LC_MEASUREMENT=de_DE.UTF-8
LC_IDENTIFICATION=de_DE.UTF-8
LC_ALL=

$ cat /etc/default/locale
# File generated by update-locale
LANG="fr_FR.UTF-8"
LC_NUMERIC="de_DE.UTF-8"
LC_TIME="de_DE.UTF-8"
LC_MONETARY="de_DE.UTF-8"
LC_PAPER="de_DE.UTF-8"
LC_NAME="de_DE.UTF-8"
LC_ADDRESS="de_DE.UTF-8"
LC_TELEPHONE="de_DE.UTF-8"
LC_MEASUREMENT="de_DE.UTF-8"
LC_IDENTIFICATION="de_DE.UTF-8"

/var/lib/AccountsService/users/martin has nothing language related, and I don't have a ~/.pam_environment, so I don't actually know where the LANGUAGE=fr_FR comes from. There are no grep results in $HOME, /etc/, or /var except for the oem-config.log.

"locale -a" actually shows that all German, French, and English locales are available. I'm not entirely sure why the desktop is English in that case (I had expected LC_MESSAGES, i. e. the LANG

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: oem-config (not installed)
ProcVersionSignature: Ubuntu 4.8.0-22.24-generic 4.8.0
Uname: Linux 4.8.0-22-generic x86_64
ApportVersion: 2.20.3-0ubuntu8
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Oct 13 09:29:02 2016
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity initrd=/casper/initrd.lz quiet splash --- debian-installer/language=de keyboard-configuration/layoutcode?=de oem-config/enable=true
InstallationDate: Installed on 2016-10-13 (0 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)