[FIX] mass-mailing: avoid ETA date jumping in the past
[FIX] mass-mailing: avoid ETA date jumping in the past

The ETA displayed on a mailing should only switch from the scheduled
date to the next cron run when the cron run is after the scheduled date.

Previously it could jump in the past on the scheduled date, if the next
cron run was in the past (delayed or in progress).

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo