∴ ./missing-filter-bug.zsh
Regular filter for null_value=true, existence=false
{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0
  },
  "hits" : {
    "total" : 2,
    "max_score" : 1.0,
    "hits" : [ {
      "_index" : "missing-test",
      "_type" : "doc",
      "_id" : "1",
      "_score" : 1.0, "_source" : { "id": "1" }
    }, {
      "_index" : "missing-test",
      "_type" : "doc",
      "_id" : "2",
      "_score" : 1.0, "_source" : { "id": "2", "myfield": "foo" }
    } ]
  }
}
Filtered query with filter for null_value=true, existence=false
{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0
  },
  "hits" : {
    "total" : 0,
    "max_score" : null,
    "hits" : [ ]
  }
}