'guix install' downloads all outputs for packages with cmake build system.

'guix install' downloads all outputs for packages with cmake build system.

[nigko]

Hello Guix!

I have found that a command 'guix install <package>' with a package having
  (1) cmake build system
  (2) (length outputs) > 1
would download all outputs of the package from a substitute server, not
just "out" output as it should.

For example, a package 'x265', which has 'static' and 'out' outputs and
cmake build system gives:
------------------------------------------------------------------------
# don't forget to insure that /gnu/store does not already contain
# x265's static output before running this command:
$ guix install x265
The following package will be installed:
   x265 3.5
...
2,8 MB will be downloaded
 x265-3.5-static  1.3MiB
 x265-3.5  1.4MiB
...
------------------------------------------------------------------------

There are 84 packages in the main guix repository satisfying (1) and (2)
criteria . Here is the full list of their names for you to try:

apache-arrow
argagg
arx-libertatis
bctoolbox
bcunit
belcard
belle-sip
belr
ceph
cmake
dealii
dealii-openmpi
dhtnet
dino
discregrid
fcitx
fcitx5-chinese-addons
fcitx5-gtk
gdcm
gemmi
gnucash
grpc
insight-toolkit
java-antlr4-runtime-cpp
libavif
libdecaf
libftdi
libgit2
liblinphone
libssh
lime
llvm
llvm-for-mesa
llvm-for-rocm
mariadb
mediastreamer2
mmg
mympd
openscenegraph
ortp
protobuf
pt-scotch
pt-scotch-shared
pt-scotch32
qtbase
qtdeclarative
scotch
scotch-shared
scotch32
sortmerna
supercollider
tidy
tidy-html
transmission
webkitgtk
webkitgtk-for-gtk3
webkitgtk-with-libsoup2
weechat
woff2
wpewebkit
x265

An interesting bit about this abnormal behavior was gained from the
discusstion on IRC. It turns out that the command
'guix install --no-grafts <package>' with --no-grafts flag does not
download all the outputs of the package but only the "out" output,
as one would expect from 'guix install' command. So the issue seems
to be related to grafts. What do you think?

Regards,
Nigko