[MESOS-7922] Fix communication between old masters and new agents.

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 1.4.0
• Component/s: agent, master
• Target Version/s: 1.4.0
• Epic Link: reservation refinement
• Sprint: Mesosphere Sprint 62
• Story Points: 2
• Assignee: Michael Park
• Reporter: Michael Park
• Shepherd: Greg Mann
• Created: 28/Aug/17 18:30
• Updated: 28/Aug/17 23:42
• Resolved: 28/Aug/17 23:42

Description

For re-registration, agents currently send the resources in tasks
and executors to the master in the "post-reservation-refinement" format,
which is incompatible for pre-1.4 masters. We should change the agent
such that it always downgrades the resources to
the "pre-reservation-refinement" format, and the master unconditionally
upgrade the resources to "post-reservation-refinement" format.