OVERLAP_DURATION not getting set for small values

[bimal-gupta]

Have observed that expire_previous_secrets_at is not being set in [POST] https://clients.oauth.cimpress.io/v1/clients/{client_id}/secrets/ when OVERLAP_DURATION is set for small values such as P0D, PT1S, PT0S. Verified the above behavior by checking entries at below endpoint:

[GET] https://clients.oauth.cimpress.io/v1/clients/{client_id}/secrets/

Also in addition to above, the previous cached token is not refreshed even if the expiry was instantenous.

The OVERLAP_DURATION seems to be working for PT5M. Maybe the value is becoming a past timestamp by the time API call goes through, just my guess.