View with reduce and ?group=false

Couchbase Server
1

couchbase 5.0.1

Why reduce function is invoked when group=false?

$ curl -s -uteligent:teligent "http://0:8092/StaticProfile/_design/muia/_view/donor?group=false" 
{"rows":[
{"key":null,"value":{"reduction_error":"308>100 acceptors  (can not index this donor)!"}}
]
}

this text comes from my (rather crude) reduce function:

function (keys, values, rereduce) { 
  var acceptors = 0
  values.forEach(function(object) {
    for (var key in object)
      acceptors += 1
  })

  if(acceptors>100)
    return {"reduction_error": acceptors + ">100 acceptors  (can not index this donor)!"}

  var out = {}
  values.forEach(function(object) {
    for (var key in object)
      out[key] = object[key]
  })
  return out
}