Description: This flag causes the values in package_group's packages attribute to no longer have the leading "//" stripped when output in bazel query --output=proto (or --output=xml). For instance, //pkg/foo would previously output as "pkg/foo". This bug did not arise for package specifications that live outside the main repo, which always printed as "@repo//pkg/foo".

Migration: Any tooling that consumes the query proto or xml formats must be able to tolerate package specification strings with leading double-slashes. This has no impact on the build itself (except possibly via genquery).

Rationale: This is a prerequisite to #16355, to avoid ambiguity between "public" and "//public".