Fail to emerge dde-extra/deepin-grub2-themes

[Anard]

Even when USE flag "grub" isn't selected, dde-meta tries to install dde-extra/deepin-grub2-themes-1.0.0 and fails on creating symlink :

$ sudo emerge -aN dde-meta
[...]
[ebuild  N    ~] dde-base/dde-meta-20  USE="elogind kwin manual policykit terminal -extra -grub -multimedia -mutter -plymouth -screensaver -systemd -terminal-old -turbo" 
[...]
>>> Emerging (4 of 202) dde-extra/deepin-grub2-themes-1.0.0::deepin
 * deepin-grub2-themes-1.0.0.tar.gz SHA256 SHA512 size ;-) ...           [ ok ]
>>> Unpacking source...
>>> Unpacking deepin-grub2-themes-1.0.0.tar.gz to /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/work
>>> Source unpacked in /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/work
>>> Preparing source in /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/work/deepin-grub2-themes-1.0.0 ...
>>> Source prepared.
>>> Configuring source in /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/work/deepin-grub2-themes-1.0.0 ...
>>> Source configured.
>>> Compiling source in /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/work/deepin-grub2-themes-1.0.0 ...
>>> Source compiled.
>>> Test phase [not enabled]: dde-extra/deepin-grub2-themes-1.0.0

>>> Install dde-extra/deepin-grub2-themes-1.0.0 into /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/image/
make -j9 DESTDIR=/var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/image/ install 
install -dm755 /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/image//boot/grub/themes
Fixing permission of files...
>>> Completed installing dde-extra/deepin-grub2-themes-1.0.0 into /var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/image/

 * Final size of build directory: 3756 KiB (3.6 MiB)
 * Final size of installed tree:  3704 KiB (3.6 MiB)

>>> Installing (4 of 202) dde-extra/deepin-grub2-themes-1.0.0::deepin
 * Your boot partition was detected as being mounted at /boot.
 * Files will be installed there for deepin-grub2-themes to function correctly.
gtk-update-icon-cache: The generated cache was invalid.
!!! failed to properly create symlink:
!!! /boot/grub/themes/deepin/background_source -> background_origin_source
!!! [Errno 1] Operation not permitted: b'background_origin_source' -> b'/boot/grub/themes/deepin/background_source'
!!! Failed to move file.
!!! /boot/grub/themes/deepin/background_source -> background_origin_source

>>> Failed to install dde-extra/deepin-grub2-themes-1.0.0, Log file:

>>>  '/var/tmp/portage/dde-extra/deepin-grub2-themes-1.0.0/temp/build.log'
$

[Anard]

solved by using /boot on / and not on differrent partition.