Broken numeric boost

boost.sh

#!/bin/sh
curl -XDELETE localhost:9200/relevance
echo
curl -XPUT localhost:9200/relevance -d '{
  "settings" : {
    "index" : {
        "number_of_shards" : 1,
        "number_of_replicas" : 0
    }    
  },
  "mappings" : {
    "doc" : {
      "properties" : {
        "important_int": {
          "type" : "integer",
          "store": "yes",
          "boost": 1.2
        },
        "unimportant_int": {
          "type" : "integer",
          "store": "yes"
        }
      }
    }
  }
}'
echo
curl -XPUT localhost:9200/relevance/doc/1 -d '{"important_int":5, "unimportant_int": 10}'
echo
curl -XPUT localhost:9200/relevance/doc/2 -d '{"important_int":10, "unimportant_int": 5}'
echo
curl -XPUT localhost:9200/relevance/doc/3 -d '{ "important_int":{"value":10,"_boost":10}, "unimportant_int": 5}'
echo
curl -XPOST localhost:9200/relevance/_refresh
echo
curl "localhost:9200/relevance/_search?q=important_int:5+unimportant_int:5&pretty=true&explain=false"
echo
curl "localhost:9200/relevance/_search?q=important_int:10+unimportant_int:10&pretty=true&explain=false"
echo