Error: 'workspace_root' is not allowed on invalid Label with Bazel@HEAD in CI

[sgowroji]

https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/3391#018b3b61-b0c9-44a4-9e42-89dfe7e885a1

Platform : Ubuntu, MacOS

Logs:

ERROR: /Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_closure/closure/private/BUILD:29:24: in closure_base_js_library rule //closure/private:base_lib:
Traceback (most recent call last):
    File "/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_closure/closure/compiler/closure_base_js_library.bzl", line 24, column 37, in _closure_base_js_library
        return create_closure_js_library(ctx, ctx.files.srcs)
    File "/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_closure/closure/compiler/closure_js_library.bzl", line 79, column 36, in create_closure_js_library
        return _closure_js_library_impl(
    File "/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_closure/closure/compiler/closure_js_library.bzl", line 239, column 29, in _closure_js_library_impl
        find_js_module_roots(srcs, workspace_name, label, includes),
    File "/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_closure/closure/private/defs.bzl", line 189, column 43, in find_js_module_roots
        new_bazel_version = Label("@foo//bar").workspace_root.startswith("../")
Error: 'workspace_root' is not allowed on invalid Label @[unknown repo 'foo' requested from @]//bar:bar

Steps:

git clone https://github.com/bazelbuild/rules_closure.git
git reset 7a2c91f9519c301f5adc072e5e18c4bae5273404 --hard
export USE_BAZEL_VERSION=2ddacab80af1dca3c04e74809827c47ec4bc8498
bazel build ...

CC Greenteam @fweikert

[gkdn]

Tried to repro but Bazelisk fails to download 2ddacab80af1dca3c04e74809827c47ec4bc8498

[gkdn]

BTW, I'm expecting this to be fixed by removing the related temporary code:https://github.com/bazelbuild/rules_closure/blob/7a2c91f9519c301f5adc072e5e18c4bae5273404/closure/private/defs.bzl#L189

[sgowroji]

Hi @gkdn, Would you mind sending a fix with a PR. Thanks a lot for your support.