Consider currentId when replacing/merging resources

When merging resources such as the output of a `configMapGenerator`,
we need to consider the `CurrentId`, otherwise, we cannot extend
a common base definition twice by adding different prefixes, and
then further kustomize them.

See #1442.

pkg/resmap/resmap.go

@@ -603,8 +603,10 @@ func (m *resWrangler) AbsorbAll(other ResMap) error {
 func (m *resWrangler) appendReplaceOrMerge(
 	res *resource.Resource) error {
 	id := res.CurId()
-	// Maybe also try by current id if nothing matches?
 	matches := m.GetMatchingResourcesByOriginalId(id.Equals)
+	if len(matches) == 0 {
+		matches = m.GetMatchingResourcesByCurrentId(id.Equals)
+	}
 	switch len(matches) {
 	case 0:
 		switch res.Behavior() {

pkg/target/configmaps_test.go

@@ -251,3 +251,63 @@ metadata:
   name: p2-com2-c4b8md75k9
 `)
 }
+
+func TestConfigMapGeneratorMergeNamePrefix(t *testing.T) {
+	th := kusttest_test.NewKustTestHarness(t, "/app")
+	th.WriteK("/app/base", `
+configMapGenerator:
+- name: cm
+  behavior: create
+  literals:
+  - foo=bar
+`)
+	th.WriteK("/app/o1", `
+resources:
+- ../base
+namePrefix: o1-
+`)
+	th.WriteK("/app/o2", `
+resources:
+- ../base
+nameSuffix: -o2
+`)
+	th.WriteK("/app", `
+resources:
+- o1
+- o2
+configMapGenerator:
+- name: o1-cm
+  behavior: merge
+  literals:
+  - big=bang
+- name: cm-o2
+  behavior: merge
+  literals:
+  - big=crunch
+`)
+	m, err := th.MakeKustTarget().MakeCustomizedResMap()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	th.AssertActualEqualsExpected(m, `
+apiVersion: v1
+data:
+  big: bang
+  foo: bar
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: o1-cm-28g596k77k
+---
+apiVersion: v1
+data:
+  big: crunch
+  foo: bar
+kind: ConfigMap
+metadata:
+  annotations: {}
+  labels: {}
+  name: cm-o2-gfcc59fg5m
+`)
+}