Elasticsearch head request returns 403 on read_only index

Elasticsearch head request returns 403 on read_only index

## input some test data into an index

curl -X POST http://127.0.0.1:9200/testindex/testtype/1 -d'
{
    "title":"titletest",
    "description":"testdescription"
}'

## make a head request to the index

curl -I http://127.0.0.1:9200/testindex

## should return 200

## make the index read_only

curl -XPUT http://127.0.0.1:9200/testindex/_settings -d'
{
    "index":{
        "blocks":{
            "read_only":true
        }
    }
}'

## make a head request to the index again.

curl -I http://127.0.0.1:9200/testindex

## returns 403 :\