[mcint]

Excellent descriptive analysis. Wrong, misleading title, perhaps "technically correct," but at best with a "backdoored" meaning.

It points out the need and use for build-manager tools that go a step beyond union file system layers, but track then enforce that e.g. tests cannot pollute build artifacts. Take a causal trace graph of files affecting files, in the build process, make that trace graph explicit, and then build a way to enforce that graph, or report on deviations from previous trace graphs.