anchor.diff:  {
     "policy": {
       "phases": {
  -      "warm": {
  -        "min_age": "1d",
  -        "actions": {
  -          "forcemerge": {
  -            "max_num_segments": 1
  +      "hot": {
  +        "min_age": "1d", <1>
  +        "actions": {
  +          "rollover": {
  +            "max_docs": 1
             }
           }
         },
  
positive.code:       "phase_execution": {
          "policy": "my_executing_policy",
          "modified_date_in_millis": 1538475653317,
          "version": 2, <1>
          "phase_definition": {
            "min_age": "1d",
            "actions": {
  
negative.code: // CONSOLE
  // TESTRESPONSE[skip:no way to know if we will get this response immediately]
  
  We can update `my_executing_policy` to enter the hot phase after one day.
  
  [source,js]
  ------------------------
  