Can't get vault token in post-stop task if the alloc has failed

[markasoftware-aqtc]

Nomad version

v1.9.4

Issue

If an alloc fails, a post-stop task cannot get the vault token. This breaks eg our use case where we use a post-stop task to detect if the job has failed, and if so get a slack token from vault and send an alert.

Reproduction steps

Write a job spec with a main task that fails and a poststop task that uses vault:

job "mork-job" {
  type = "batch"

  group "mork-group" {
    task "main" {
      driver = "exec"
      config {
        command = "false"
      }
    }

    task "post-stop" {
      driver = "exec"
      config {
        command = "true"
      }

      lifecycle {
        hook = "poststop"
      }

      vault {
        policies = ["foo"]
      }
    }
  }
}

Expected Result

Vault access succeeds.

Actual Result

Error Vault: server failed to derive vault token: Can't request Vault token for terminal allocation