Ben Gamari authored Mar 15, 2019 and Marge Bot committed Mar 20, 2019

The `build` stage is meant to be a minimal smoke test to weed out broken
commits. The `validate-x86_64-linux-deb9` build will generally catch a
subset of issues caught by `validate-x86_64-linux-deb9-debug` so only
the latter should be in `build`.