configMapGenerator merge ignores previous namePrefix applications

[jcpetruzza]

From kustomization c, I want to extend a configMap imported from resource b, where a name-prefix was added to a configMap originally defined in a. I expect to use b's name to denote the name of the configMap, but have to use a's instead. Full example:

$ cat a/kustomization.yaml
configMapGenerator:
- name: cm
  literals:
  - FOO=BAR

$ cat b/kustomization.yaml
resources:
- ../a
namePrefix: renamed-

$ cat c/kustomization.yaml
resources:
- ../b
configMapGenerator:
- name: cm   # <-- should be renamed-cm!
  behavior: merge
  literals:
  - HELLO=WORLD

$ kustomize build c
apiVersion: v1
data:
  FOO: BAR
  HELLO: WORLD
kind: ConfigMap
metadata:
  annotations: {}
  labels: {}
  name: renamed-cm-27kg5g5b5c

Notice that if I use renamed-cm in c/kustomization.yaml, I get this error:

Error: merging from generator &{0xc0000eeb40 0xc0004d5a60 { } {map[] map[] false} {{ renamed-cm merge {[HELLO=WORLD] [] [] }}}}: id resid.ResId{Gvk:gvk.Gvk{Group:"", Version:"v1", Kind:"ConfigMap"}, Name:"renamed-cm", Namespace:""} does not exist; cannot merge or replace

This is not only confusing, it also means that one cannot define a base configMap, produce two different versions of it with namePrefix, and then extend only one (actually, one can't even extend both at the same time, since kustomize will fail with found multiple objects ... that could accept merge of ...).

$ kustomize version                                                                                                                                 
Version: {KustomizeVersion:3.1.0 GitCommit:95f3303493fdea243ae83b767978092396169baf BuildDate:unknown GoOs:linux GoArch:amd64}