GSI index drop query fails with Request timed out

Steps:

• Create 300M docs in a bucket
• Create an moi index and issue a Drop index command in cbq shell. The query fails with -
  cbq> drop index default.i2;
  {
  "requestID": "b7b4105f-da43-48e1-adb1-6fbcfd93032d",
  "signature": null,
  "results": [
  ],
  "errors": [ { "code": 5000, "msg": "GSI Drop() - cause: Request timed out. Index server may still be processing this request. Please check the status after sometime or retry." }

  ],
  "status": "errors",
  "metrics":

  { "elapsedTime": "2m0.855236938s", "executionTime": "2m0.855153302s", "resultCount": 0, "resultSize": 0, "errorCount": 1 }

  }

indexer log attached. Timestamp to look at: 2016-04-01T15:10:42.572+05:30