We don't want LLVM 8 packages to be pulled in from testing though (it would make installing llvm-8-dev for cross architectures a lot more complicated), so explicitly select buster-backports for them (they were already implicitly installed from there before, since they're not available in buster proper).
fd9b4451458 gitlab-ci: Add Debian testing repository for x86_build image
.gitlab-ci.yml | 2 +-
.gitlab-ci/container/x86_build.sh | 22 ++++++++++++++++++----
2 files changed, 19 insertions(+), 5 deletions(-)