anchor.diff:  
   ===== Examples of unassigned primary shard explanations
   
  -[source,console]
  ---------------------------------------------------
  -PUT /idx?master_timeout=1s&timeout=1s
  +//////
  +[source,console]
  +--------------------------------------------------	
  +DELETE myindex	
  +--------------------------------------------------	
  +//////
  +
  +[source,console]
  +--------------------------------------------------
  +PUT /my_index?master_timeout=1s&timeout=1s
   {"settings": {"index.routing.allocation.include._name": "non_existent_node"} }
   
   GET /_cluster/allocation/explain
   {
  -  "index": "idx",
  +  "index": "my_index",
     "shard": 0,
     "primary": true
   }
  
positive.code: [source,console-result]
  --------------------------------------------------
  {
    "index" : "idx",
    "shard" : 0,
    "primary" : true,
    "current_state" : "unassigned",                 <1>
  
negative.code:         {
            "decider" : "same_shard",
            "decision" : "NO",
            "explanation" : "the shard cannot be allocated to the same node on which a copy of the shard already exists [[my_index][0], node[3sULLVJrRneSg0EfBB-2Ew], [P], s[STARTED], a[id=eV9P8BN1QPqRc3B4PLx6cg]]"
          }
        ]
      }
  