"FAILURE Failed to link ... No such file or directory" in a compose element

I get the following error

        [--:--:--] INFO    [flatpak/platform-image.bst]: Composing 99414 files
        [00:00:00] FAILURE [flatpak/platform-image.bst]: Creating composition
        [00:00:48] FAILURE [flatpak/platform-image.bst]: Failed to link '/home/abderrahim/.cache/buildstream/build/flatpak-platform-image-b2cifeac/root -> /home/abderrahim/.cache/buildstream/build/flatpak-platform-image-b2cifeac/root/buildstream/install': [Errno 2] No such file or directory: '/home/abderrahim/.cache/buildstream/build/flatpak-platform-image-b2cifeac/root/buildstream/install/etc/avahi'

What I find weird is that it doesn't make sense to me. It tries to link /root into /root/buildstream/install, but doesn't find /root/buildstream/install/etc/avahi.

This happens with the abderrahim/flatpak-sdk branch of gnome-build-meta. Here is the full build log build.log