Snippet added to ScriptElement.stage():
        run_scope_elements = [x.name for x in self.dependencies(Scope.RUN)]
        build_run_elements = set()
        for bd in self.dependencies(Scope.BUILD, recurse=False):
            build_run_elements |= set([x.name for x in bd.dependencies(Scope.RUN)])
        self.warn("Run scope elements!", detail="\n".join(sorted(run_scope_elements)))
        self.warn("Build then run elements!", detail="\n".join(sorted(build_run_elements)))
Result:
[--:--:--] WARNING [base-system-image.bst]: Run scope elements!

    base-system-image.bst
[--:--:--] WARNING [base-system-image.bst]: Build then run elements!

    base-system-x86_64-generic-content.bst
    base-system.bst
    bsp-x86_64-generic.bst
    bsp-x86_64-generic/linux-x86-64-generic.bst
    core.bst
    core/XML-Parser.bst
    core/acl.bst
    core/attr.bst
    core/autoconf-tarball.bst
    core/autoconf.bst
    core/automake.bst
    core/bash.bst
    core/bc.bst
    core/bison.bst
    core/bzip2.bst
    core/ca-certificates.bst
    core/cmake.bst
    core/curl.bst
    core/cython.bst
    core/e2fsprogs.bst
    core/file.bst
    core/flex.bst
    core/gdbm.bst
    core/gettext-tarball.bst
    core/git-minimal.bst
    core/gperf.bst
    core/help2man.bst
    core/intltool.bst
    core/libcap2.bst
    core/libexpat.bst
    core/libffi.bst
    core/libseccomp.bst
    core/libtool-tarball.bst
    core/libtool.bst
    core/libxml2.bst
    core/libxslt.bst
    core/linux-pam.bst
    core/mini-utils.bst
    core/ncurses.bst
    core/openssl-new.bst
    core/patch.bst
    core/perl.bst
    core/pkg-config.bst
    core/python3.bst
    core/readline.bst
    core/shadow.bst
    core/sqlite3.bst
    core/texinfo-tarball.bst
    core/util-linux.bst
    core/xz.bst
    coreutils-common.bst
    coreutils-common/coreutils.bst
    coreutils-common/diff.bst
    coreutils-common/findutils.bst
    coreutils-common/jq.bst
    coreutils-common/less.bst
    coreutils-common/sed.bst
    coreutils-common/tar.bst
    deploy-base.bst
    deploy-base/mtools.bst
    deploy-base/nasm.bst
    deploy-base/syslinux.bst
    docutils.bst
    docutils/asciidoc.bst
    docutils/docbook-xml.bst
    docutils/docbook-xsl.bst
    docutils/xml-catalog.bst
    docutils/xmlto.bst
    foundation.bst
    foundation/bash-completion.bst
    foundation/btrfs-progs.bst
    foundation/dbus-pre.bst
    foundation/dbus.bst
    foundation/fuse.bst
    foundation/groff.bst
    foundation/kmod.bst
    foundation/libarchive.bst
    foundation/libgcrypt.bst
    foundation/libgpg-error.bst
    foundation/libusb.bst
    foundation/lzo.bst
    foundation/openssh.bst
    foundation/pciutils.bst
    foundation/python-systemd.bst
    foundation/rsync.bst
    foundation/systemd.bst
    foundation/tbdiff.bst
    foundation/time-zone-database.bst
    foundation/usbutils.bst
    gnu-toolchain.bst
    gnu-toolchain/binutils.bst
    gnu-toolchain/busybox.bst
    gnu-toolchain/ccache.bst
    gnu-toolchain/fhs-dirs.bst
    gnu-toolchain/gawk.bst
    gnu-toolchain/gcc.bst
    gnu-toolchain/glibc.bst
    gnu-toolchain/linux-api-headers.bst
    gnu-toolchain/m4-tarball.bst
    gnu-toolchain/make.bst
    gnu-toolchain/zlib.bst
    initramfs/initramfs-gz.bst
    python2-core.bst
    python2-core/cython2.bst
    python2-core/jsonschema-python2.bst
    python2-core/libxml2-python2.bst
    python2-core/mako-python2.bst
    python2-core/pbr-python2.bst
    python2-core/python2-lxml.bst
    python2-core/python2-markdown.bst
    python2-core/python2-requests.bst
    python2-core/python2-setuptools.bst
    python2-core/python2.bst
    python2-core/pyyaml-python2.bst
    python2-core/six-python2.bst
    tools.bst
    tools/device-tree-compiler.bst
    tools/distcc.bst
    tools/gdb.bst
    tools/ipmitool.bst
    tools/kexec-tools.bst
    tools/lsof.bst
    tools/parted.bst
    tools/procps-ng.bst
    tools/strace.bst
    tools/sudo.bst
    tools/u-boot.bst
    tools/zip.bst