Why does sorting fail here?

1_document.sh

curl -X PUT 'localhost:9200/test/product/4e725af8349c301b5500002e' -d '{
  "name" : "Snoprinsessa Barbie",
  "items" : [
    { "name" : "Faux fur-trimmed parka", "properties" : {"color" : "White"} },
    { "name" : "Stud Diamond Ring", "properties" : {"color" : "Clear"} }
  ]
}'

2_query.sh

curl -X GET 'localhost:9200/test/product/_search?pretty=true' -d '{
  "sort" : [{ "items.properties.color.orig": {"order": "asc"} }]
}'
{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 4,
    "failed" : 1,
    "failures" : [ {
      "index" : "test",
      "shard" : 2,
      "status" : 500,
      "reason" : "QueryPhaseExecutionException[[test][2]: query[ConstantScore(*:*)],from[0],size[10],sort[<custom:\"items.properties.color.orig\": org.elasticsearch.index.field.data.strings.StringFieldDataType$1@1b61aea>]: Query Failed [Failed to execute main query]]; nested: IOException[Can't sort on string types with more than one value per doc, or more than one token per field]; "
    } ]
  },
  "hits" : {
    "total" : 0,
    "max_score" : null,
    "hits" : [ ]
  }
}

3_settings.sh

curl -X DELETE 'localhost:9200/test'

curl -X PUT 'localhost:9200/test' -d '{
  "settings": {
    "analysis": {

      "filter": {
        "edge_ngram": {
          "type":     "edgeNGram",
          "side":     "front",
          "max_gram": 20,
          "min_gram": 1
        }
      },

      "analyzer": {

        "ascii_std": {
          "type":       "custom",
          "tokenizer":  "standard",
          "filter":     ["standard", "lowercase", "asciifolding"]
        },

        "ascii_edge_ngram": {
          "type":       "custom",
          "tokenizer":  "standard",
          "filter":     ["standard", "lowercase", "asciifolding", "edge_ngram"]
        }
      }
    }
  }
}'

4_mapping.sh

curl -X GET 'localhost:9200/test/product/_mapping?pretty=true'
{
  "product" : {
    "properties" : {
      "items" : {
        "properties" : {
          "name" : {
            "type" : "string"
          },
          "properties" : {
            "properties" : {
              "color" : {
                "type" : "multi_field",
                "fields" : {
                  "color" : {
                    "include_in_all" : true,
                    "index_analyzer" : "ascii_edge_ngram",
                    "search_analyzer" : "ascii_std",
                    "type" : "string"
                  },
                  "orig" : {
                    "include_in_all" : false,
                    "index" : "not_analyzed",
                    "type" : "string"
                  }
                }
              }
            }
          }
        }
      },
      "name" : {
        "type" : "string"
      }
    }
  }
}