Source filtering with wildcards broken when given multiple patterns

```
curl -XPUT 'http://localhost:9200/twitter/tweet/1' -d '{
    "user" : "kimchy",
    "post_date" : "2009-11-15T14:12:12",
    "message" : "trying out Elasticsearch", "retweeted": false
}'
```

No source fields delivered:

```
curl -XGET 'http://localhost:9200/twitter/tweet/1?_source=*.id,retweeted&pretty=yes'
```

`retweeted` returned:

```
curl -XGET 'http://localhost:9200/twitter/tweet/1?_source=retweeted,*.id&pretty=yes'
```

Closes #5132.