appendCsVAnnotation must mutate the annotations RNode in place

Otherwise, it is incompatible with filters like fieldSpec.Filter that recurse through a tree of RNodes. In the case of the bug this commit fixes, the leaf RNode is a metadata.annotation value field, and appendCsvAnnotation is called immediately before updating that leaf's value. If appendCsvAnnotation replaces the entire metadata.annotation RNode on the resource, the leaf RNode that gets updated is no longer attached to the resource.

Alternatively, `func (f Filter) setScalar` could be updated to change
the value of the leaf RNode BEFORE calling appendCsvAnnotation. However,
the modification of the entire metadata segment of the RNode in a
function that nominally just edits an annotation feels like a
side-effect prone to creating other difficult-to-debug situations,
beyond this ordering dependency.

api/krusty/namereference_test.go

@@ -649,7 +649,6 @@ metadata:
   name: oldNs
 `)
 	m := th.Run(".", th.MakeDefaultOptions())
-	// Incorrect: the self-reference annotations in both resources were not updated!
 	th.AssertActualEqualsExpected(m, `
 apiVersion: v1
 data:
@@ -658,7 +657,7 @@ data:
 kind: ConfigMap
 metadata:
   annotations:
-    theConfigMap: cm
+    theConfigMap: cm-updated
     theNamespace: newNs
   name: cm-updated
   namespace: newNs
@@ -668,7 +667,7 @@ kind: Namespace
 metadata:
   annotations:
     theConfigMap: cm-updated
-    theNamespace: oldNs
+    theNamespace: newNs
   name: newNs
 `)
 }

api/resource/resource.go

@@ -255,13 +255,9 @@ func (r *Resource) appendCsvAnnotation(name, value string) {
 	if value == "" {
 		return
 	}
-	annotations := r.GetAnnotations()
-	if existing, ok := annotations[name]; ok {
-		annotations[name] = existing + "," + value
-	} else {
-		annotations[name] = value
-	}
-	if err := r.SetAnnotations(annotations); err != nil {
+	currentValue := r.getCsvAnnotation(name)
+	newValue := strings.Join(append(currentValue, value), ",")
+	if err := r.RNode.PipeE(kyaml.SetAnnotation(name, newValue)); err != nil {
 		panic(err)
 	}
 }

api/resource/resource_test.go

@@ -1402,31 +1402,31 @@ spec:
 `))
 	assert.NoError(t, err)
 	r.AppendRefBy(resid.FromString("knd1.ver1.gr1/name1.ns1"))
-	assert.Equal(t, r.RNode.MustString(), `apiVersion: v1
+	assert.Equal(t, `apiVersion: v1
 kind: Deployment
 metadata:
   name: clown
   annotations:
-    internal.config.kubernetes.io/refBy: knd1.ver1.gr1/name1.ns1
+    internal.config.kubernetes.io/refBy: 'knd1.ver1.gr1/name1.ns1'
 spec:
   numReplicas: 1
-`)
+`, r.RNode.MustString())
 	assert.Equal(t, r.GetRefBy(), []resid.ResId{resid.FromString("knd1.ver1.gr1/name1.ns1")})
 
 	r.AppendRefBy(resid.FromString("knd2.ver2.gr2/name2.ns2"))
-	assert.Equal(t, r.RNode.MustString(), `apiVersion: v1
+	assert.Equal(t, `apiVersion: v1
 kind: Deployment
 metadata:
   name: clown
   annotations:
-    internal.config.kubernetes.io/refBy: knd1.ver1.gr1/name1.ns1,knd2.ver2.gr2/name2.ns2
+    internal.config.kubernetes.io/refBy: 'knd1.ver1.gr1/name1.ns1,knd2.ver2.gr2/name2.ns2'
 spec:
   numReplicas: 1
-`)
-	assert.Equal(t, r.GetRefBy(), []resid.ResId{
+`, r.RNode.MustString())
+	assert.Equal(t, []resid.ResId{
 		resid.FromString("knd1.ver1.gr1/name1.ns1"),
 		resid.FromString("knd2.ver2.gr2/name2.ns2"),
-	})
+	}, r.GetRefBy())
 }
 
 func TestOrigin(t *testing.T) {