Fixes <http://bugs.gnu.org/25100

>.

Before that, 'guix system reconfigure' would fail if the next generation
already existed.

* guix/scripts/system.scm (switch-to-system): Use 'switch-symlink'
instead of 'symlink'.
* doc/guix.texi (Using the Configuration System, Invoking guix system):
Document the behavior.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

* gnu/packages/wm.scm (i3-wm): Update to 4.13.
[arguments]: Pass '-std=c11' to #:make-flags. Provide path to XML_CATALOG_FILES.
Pass '--disable-builddir' to #:configure-flags. Re-enable the 'configure' phase
to adjust to new Autotools build system.
[inputs]: Add xcb-util-xrm.
[native-inputs]: Add docbook-xsl.

* gnu/packages/xorg.scm (xcb-util-cursor)[inputs]: Move xcb-util-renderutil and
xcb-util-image to ...
[propagated-inputs]: ... here.

* gnu/packages/ruby.scm (ruby-2.2, ruby-2.1, ruby-1.8)[replacement]: New field.

* gnu/packages/package-management.scm (guix-devel): Update to 9328eafb.

Fixes a regression introduced in
bf7ef1bb, whereby the fsck.* commands
would not be found.

* gnu/services/base.scm (file-system-shepherd-service): Call calls to
'setenv'.

This is a followup to d1a5b200.

* po/packages/POTFILES.in: Remove gnu/packages/geeqie.scm.

* guix/scripts/refresh.scm (show-help): Add brackets around PACKAGE.

* gnu/packages/linux.scm (fuse-exfat): Update to 1.2.5.
[native-inputs]: Remove scons build system which is no longer used.
[arguments]: Remove.
[home-page]: Replace dead Google Code home page.

* gnu/packages/mtools.scm (exfat-utils): Update to 1.2.5.

* gnu/packages/bittorrent.scm (mktorrent): New variable.

* guix/scripts/offload.scm (assert-node-repl, assert-node-has-guix)
(nonce, assert-node-can-import, assert-node-can-export)
(check-machine-availability): New procedures.
(%random-state): New variable.
(guix-offload): Add case for "test".
* doc/guix.texi (Daemon Offload Setup): Document it.  Remove obsolete
bit about remote invocation of 'guix build'.

* nix/libstore/optimise-store.cc (LocalStore::optimisePath_): Use %3%
instead of %m, the latter being an invalid Boost format specifier.

* gnu/packages/python.scm (python-flask, python2-flask)[native-inputs]: Move
python-click to ...
[propagated-inputs]: ... here.

* gnu/packages/admin.scm (shepherd): Update to 0.3.2.
[properties]: New field.

This is a followup to d1a5b200.

* po/packages/POTFILES.in: Remove feh.scm and add image-viewers.scm.

* guix/scripts/publish.scm (with-content-length): New procedure.
(http-write) <application/octet-stream>: Use it.

* gnu/services/networking.scm (tor-hidden-service-activation): Add
'chmod' call for /var/lib.

* gnu/packages/vim.scm (vim, vim-full): Update to 8.0.0124.

* gnu/packages/mail.scm (dovecot): Update to 2.2.27.
[source, home-page]: Use HTTPS.

* gnu/packages/vim.scm (vim, vim-full): Update to 8.0.0118.

* gnu/packages/music.scm (qmidiarp): New variable.

* gnu/packages/aspell.scm (aspell-dict-sv): New variable.

Signed-off-by: Marius Bakke <mbakke@fastmail.com>

* gnu/packages/feh.scm (feh): Remove file.  Move package to...
* gnu/packages/geeqie.scm (geeqie): Likewise...
* gnu/packages/sxiv.scm (sxiv): Likewise...
* gnu/packages/image-viewers.scm: ... here.
* gnu/local.mk (GNU_SYSTEM_MODULES): Remove files.

* gnu/packages/geeqie.scm (exiv2): Move to...
* gnu/packages/image.scm: ... here.
* gnu/packages/gnome.scm: Adjust the used modules.
* gnu/packages/gnunet.scm: Likewise.
* gnu/packages/gps.scm: Likewise.

* gnu/packages/emacs.scm (emms): Update to 4.2.
[arguments]: EMMS installs "emms-print-metadata" now but assumes that
BINDIR exists, so do not install it manually in 'post-install' phase,
and make "/bin" directory in 'pre-install' phase.

* gnu/packages/emacs.scm (emacs-with-editor): Update to 2.5.6.

* gnu/packages/emacs.scm (emacs-hl-todo): Update to 1.7.4.

* gnu/packages/music.scm (ingen): New variable.

* gnu/packages/audio.scm (raul-devel): New variable.

* gnu/packages/gtk.scm (ganv-devel): New variable.

* gnu/packages/music.scm (ams-lv2): New variable.

* gnu/packages/audio.scm (lvtk)[inputs]: Add gtkmm-2.
[arguments]: Pass "-std=c++11" flag.

* gnu/packages/golang.scm: Replace header line declaring this file as
part of GNU Guix.

* gnu/packages/connman.scm (econnman): New variable.

* gnu/packages/enlightenment.scm (lekha): New variable.

* gnu/packages/sync.scm (qsyncthingtray): New variable.

* gnu/packages/owncloud.scm: Rename to ...
* gnu/packages/sync.scm: ... this.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register it.