The comments at the start of src/cmd/vet/dead.go don't have completely blank lines so they are treated as package-level documentation.

What did you do?

go doc vet

What did you expect to see?

Package-level documentation

What did you see instead?

The Go Authors copyright message and "Simplified dead code detector. Used for skipping certain checks on unreachable code (for instance, shift checks on arch-specific code)."

System details

master branch