The final stage is scratch, which has no C library, but the builder
compiled mfer with cgo on (the golang image's default). google/uuid
imports net, so the binary came out dynamically linked and the image
could not start. The image's go build now sets CGO_ENABLED=0; nothing
in mfer needs cgo. A new builder step runs ldd on the binary and fails
the build unless it reports a static executable.
Model: opus-5-5
sneak