Bug#697765: dpkg-reconfigure -fnoninteractive locales fails

[Christian Meyer <c2h5oh@web.de>]

Dear maintainers,
I badly got bitten by this bug, too, while trying to (automatically)
install Debian Jessie (stable) with FAI.

When installing locales and then reconfiguring it with
# dpkg-reconfigure locales
it works as expected using dialog input method.

Trying to reconfigure locales noninteractively, it fails:

# echo "set locales/locales_to_be_generated de_DE.UTF-8 UTF-8" | chroot
$NFSROOT debconf-communicate
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "de_DE.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or
directory
locale: Cannot set LC_ALL to default locale: No such file or directory
0 value set

# echo "set locales/default_environment_locale de_DE.UTF-8" | chroot
$NFSROOT debconf-communicate
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "de_DE.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or
directory
locale: Cannot set LC_ALL to default locale: No such file or directory
0 value set

# chroot $NFSROOT dpkg-reconfigure -fnoninteractive locales
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "de_DE.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or
directory

Workaround (thanks to Thomas Lange from FAI):
Don't install locales with all the other packages but seperately (e. g.
with a script). Configure locales before installation. Do not
reconfigure them (noninteractively).
https://lists.uni-koeln.de/pipermail/linux-fai/2015-May/thread.html#10890
https://lists.uni-koeln.de/pipermail/linux-fai/2015-May/010922.html

Thanks for attention.
Christian