Retry requesting status up to 5 consecutive times when getting 5xx er…

Created by: valentindavid

…rors

This should help gitlab in periods where gitlab has network issues. That happens once in a while, and during this time there are few 5xx errors (502 and 504). When one happens on a MR status request, then Marge just unassign the MR, or close and re-opens a new batch. When 5xx errors happen every 10 minutes, nothing gets merged.