Relative references in a schema without id causes infinite recursion.

[henrikp-visma]

Reproducible with a schema like this

{
  "type": "object",
  "properties": {
    "mything": {"$ref": "#thing"} 
  },
  "definitions": {
    "thing": {
      "id": "#thing",
      "type": "string"
    }
  }
}

When validating an instance with code like

val validator = SchemaValidator()
validator.validate(schemaUrl, instance)

the validation is stuck in an infinite recursion and runs out of stack.
If id is given for the schema, the validation finishes correcly.

[edgarmueller]

Fixed with 0.8.8