could not determine interactive username: number of gnome session users is not exactly one

[bhearsum]

Noticed this error showing up in Firefox CI:

could not determine interactive username: number of gnome session users is not exactly one - not sure which user is interactively logged on: []string{""}

{
  "GOOS": "linux",
  "GOARCH": "amd64",
  "engine": "multiuser",
  "rootURL": "https://firefox-ci-tc.services.mozilla.com",
  "workerId": "9144889771845100298",
  "gwVersion": "64.2.0",
  "gwRevision": "9a9e590f97a3cab828ec1ea933610ce71d334c11",
  "workerType": "b-linux-large-gcp-d2g",
  "workerGroup": "us-central1-c",
  "deploymentId": "",
  "instanceType": "projects/887720501152/machineTypes/n2-highmem-32",
  "provisionerId": "translations-1",
  "cleanUpTaskDirs": "true"
}

It's not super frequent, but also not a one off. Seen in pools such as https://firefox-ci-tc.services.mozilla.com/worker-manager/translations-1%2Fb-linux-large-gcp-d2g/errors.