behaviour of os.Root Remove method

Is it permitted to use the Remove method of os.Root to remove the base directory opened by os.OpenRoot? In other words, what should be the result of this snippet?

  root,  _ := os.OpenRoot("/tmp/foo")

  root.Remove(".")

Is it forbidden? Permitted, but might not work depending on the OS (like attempting to Remove the current working directory)? Or permitted and expected to work everywhere?

I can't find anything in the package documentation to say that applying Remove to the base directory is forbidden. But CL 661595 added a test TestRootRemoveDot which expects this operation to fail. This breaks Plan 9 builders, where the operation doesn't fail (as reported in #73863 about 10 days ago).

I'd like to fix this so Plan 9 builds can resume. But I don't know whether the correct fix is to make Remove on Plan 9 check for removing the base directory, to skip the test on Plan 9, or to remove the test altogether (because it's testing an OS restriction, not testing a defined go behaviour).

Can someone with authority please advise?