Fixes <http://bugs.gnu.org/20646>.
Reported by David Thompson <davet@gnu.org>.
* gnu/system/shadow.scm (assert-valid-users/groups): New procedure
* gnu/system.scm (operating-system-activation-script): Use it.
* tests/guix-system.sh (make_user_config): New function.
Add 3 tests using it.
* po/guix/POTFILES.in: Add gnu/system/shadow.scm.
Reported by 白い熊 @相撲道 <guix-devel_gnu.org@sumou.com>
at <http://lists.gnu.org/archive/html/guix-devel/2015-03/msg00264.html>.
* gnu/services/dmd.scm (assert-no-duplicates): New procedure.
(dmd-configuration-file): Use it.
* po/guix/POTFILES.in: Add gnu/services/dmd.scm.
* tests/guix-system.sh (errorfile): Add test.
* gnu/system/locale.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
* gnu/system.scm (<operating-system>)[locale]: Change the default to
"en_US.utf8".
(operating-system-locale-directory): New procecure.
(operating-system-derivation): Use it.
* doc/guix.texi (Using the Configuration System): Change example locale
to "fr_FR.utf8".
(operating-system Reference): Add xref to "Locales". Document
'locale-definitions'.
(Locales): New section.
* po/guix/POTFILES.in: Add gnu/system.scm.
