GCE auth fails in Vault 1.0.0

[mjrlee]

Describe the bug
After upgrading Vault from 0.11.5, GCE auth failed, with the following error returned from Vault:

{"errors":["could not find service account \"[redacted]\" in project \"\": googleapi: Error 400: The name should be in the form \"projects/{project_id}/serviceAccounts/{account}\"., badRequest"]}

After rolling back to 0.11.5, the project_id Key of my roles at /auth/gcp/role/foo was missing. I wrote them again and this resolved that problem.

Environment:

• Vault Server Version (retrieve with vault status):
  Vault 1.0.0