ElasticSearch bug with dots in document type?

cmd.sh

curl -XPUT 'http://localhost:9200/twitter/twee.t/1' -d '{
    "user" : "kimchy",
    "post_date" : "2009-11-15T14:12:12",
    "message" : "trying out Elasticsearch"
}'

curl -X GET 'http://localhost:9200/twitter/_search?q=user:kimchy'
curl -X GET 'http://localhost:9200/twitter/twee.t/_search?q=user:kimchy'
curl -X GET 'http://localhost:9200/twitter/tw*/_search?q=user:kimchy'

First two work and return data, the third doesn't but should according to wildcards. http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/multi-index-multi-type.html

curl -XGET "http://localhost:9200/twitter/_search" -d'
{
    "query": {
        "filtered": {
           "filter": {
               "regexp": {
                   "_type": {
                      "value": "tw.*"
                   }
                }
           }
        }
    }
}'