When an AM is assigned a FAILED_MAP (priority = 5) container on a nodemanager which it has blacklisted - it tries to
find a corresponding container request.
This uses the hostname to find the matching container request - and can end up returning any of the ContainerRequests which may have requested a container on this node. This container request is cleaned to remove the bad node - and then added back to the RM 'ask' list.
The AM cleans the 'ask' list after each heartbeat - The RM Allocator is still aware of the priority=5 container (in 'remoteRequestsTable') - but this never gets added back to the 'ask' set - which is what is sent to the RM.