Completion type mapping is not idempotent

[missinglink]

Completion mapping is not idempotent in the same way other field types are, probably due to the internal re-ordering of the precision array.

In the example below you can see that updating the mapping twice causes an error, if you start afresh and use the precision values [ 1,2,3 ] the issue goes away.

Note when you PUT the mapping as below and then GET it back you'll notice the ordering of the precision array is now [2,3,1,4].

#!/bin/bash

################################################
# Completion Mapping Idempotence
################################################

ES='localhost:9200';

# drop/create index
curl -s -XDELETE "$ES/testcase?pretty=true" >/dev/null;
curl -s -XPUT "$ES/testcase?pretty=true" >/dev/null;

# update mapping
update_mapping() {
  curl -s -XPUT "$ES/testcase/_mapping/mytype?pretty=true" -d '
  {
     "properties": {
        "suggest": {
           "type": "completion",
           "context": {
              "location": {
                 "type": "geo",
                 "precision": [ 1, 2, 3, 4 ]
              }
           }
        }
     }
  }';
}

update_mapping;
# "acknowledged" : true

update_mapping;
# "error" : "MergeMappingException[Merge failed with failures {[mapper [suggest] has different 'context_mapping' values]}]"

curl -s "$ES/testcase/mytype/_mapping?pretty=true" | grep precision
# "precision" : [ 2, 3, 1, 4 ]

cc/ @markharwood as it may be related to c0aef4a and @areek as it relates to context suggesters

[missinglink]

curl -s localhost:9200/
{
  "status" : 200,
  "name" : "Alcmena",
  "version" : {
    "number" : "1.3.4",
    "build_hash" : "a70f3ccb52200f8f2c87e9c370c6597448eb3e45",
    "build_timestamp" : "2014-09-30T09:07:17Z",
    "build_snapshot" : false,
    "lucene_version" : "4.9"
  },
  "tagline" : "You Know, for Search"
}