apiserver: Fix handling patch requests with charset

Fixes #14872

pkg/apiserver/apiserver_test.go

@@ -1659,7 +1659,7 @@ func TestPatch(t *testing.T) {
 
 	client := http.Client{}
 	request, err := http.NewRequest("PATCH", server.URL+"/api/version/namespaces/default/simple/"+ID, bytes.NewReader([]byte(`{"labels":{"foo":"bar"}}`)))
-	request.Header.Set("Content-Type", "application/merge-patch+json")
+	request.Header.Set("Content-Type", "application/merge-patch+json; charset=UTF-8")
 	_, err = client.Do(request)
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)

pkg/apiserver/resthandler.go

@@ -21,6 +21,7 @@ import (
 	"net/http"
 	"net/url"
 	gpath "path"
+	"strings"
 	"time"
 
 	"k8s.io/kubernetes/pkg/admission"
@@ -736,6 +737,10 @@ func setListSelfLink(obj runtime.Object, req *restful.Request, namer ScopeNamer)
 }
 
 func getPatchedJS(contentType string, originalJS, patchJS []byte, obj runtime.Object) ([]byte, error) {
+	// Remove "; charset=" if included in header.
+	if idx := strings.Index(contentType, ";"); idx > 0 {
+		contentType = contentType[:idx]
+	}
 	patchType := api.PatchType(contentType)
 	switch patchType {
 	case api.JSONPatchType: