Migrate all precise jobs on the job grid to trusty in several steps.
- late August 2016: Jobs started without -l release=... and webservices started with --release=precise will print a warning.
- mid October 2016: Jobs started with jsub will no longer run on Precise hosts by default, and will instead run on Trusty hosts. This means jobs running via cron will migrate to trusty automatically.
- October 2016-January 2017: Tools starting jobs with jsub -l release=precise will start receiving emails urging them to migrate to Trusty.
- March 14 2017: Jobs started with jsub -l release=precise will no longer function and will crash with an error.