Fix change node overwriting msg with itself

and add test
to close #3891

packages/node_modules/@node-red/editor-client/locales/ja/editor.json

@@ -935,11 +935,11 @@
         "errors": {
             "invalid-expr": "不正なJSONata式:\n  __message__",
             "invalid-msg": "不正なJSONメッセージ例:\n  __message__",
-            "context-unsupported": "$flowContext や $globalContextの\nコンテキスト機能をテストできません",
+            "context-unsupported": "$flowContext や $globalContextの\nコンテキスト関数をテストできません",
             "env-unsupported": "$env関数はテストできません",
             "moment-unsupported": "$moment関数はテストできません",
             "clone-unsupported": "$clone関数はテストできません",
-            "eval": "表現評価エラー:\n  __message__"
+            "eval": "式評価エラー:\n  __message__"
         }
     },
     "monaco": {

packages/node_modules/@node-red/nodes/core/function/15-change.js

@@ -318,7 +318,7 @@ module.exports = function(RED) {
             }
             var r = node.rules[currentRule];
             if (r.t === "move") {
-                if ((r.tot !== r.pt) || (r.p.indexOf(r.to) !== -1)) {
+                if ((r.tot !== r.pt) || (r.p.indexOf(r.to) !== -1) && (r.p !== r.to)) {
                     applyRule(msg,{t:"set", p:r.to, pt:r.tot, to:r.p, tot:r.pt},(err,msg) => {
                         applyRule(msg,{t:"delete", p:r.p, pt:r.pt}, (err,msg) => {
                             completeApplyingRules(msg,currentRule,done);

packages/node_modules/@node-red/nodes/locales/en-US/function/80-template.html

@@ -52,4 +52,7 @@
        used to mark the templated sections. For example, to use <code>[[ ]]</code>
        instead, add the following line to the top of the template:</p>
     <pre>{{=[[ ]]=}}</pre>
+    <h4>Using environment variables</h4>
+    <p>The template node can access environment variables using the syntax:</p>
+    <pre>My favourite colour is {{env.COLOUR}}.</pre>
 </script>

packages/node_modules/@node-red/nodes/locales/ja/function/80-template.html

@@ -48,4 +48,7 @@
     <p><b>注: </b>デフォルトでは、<i>mustache</i>形式は置換対象のHTML要素をエスケープします。これを抑止するには<code>{{{三重}}}</code>括弧形式を使います。</p>
     <p>もし、コンテンツの中で<code>{{ }}</code>を出力する必要がある場合は、テンプレートで使われる記号文字を変えることもできます。例えば、<code>[[ ]]</code>を代わりに用いるには、テンプレートの先頭に以下の行を追加します。</p>
     <pre>{{=[[ ]]=}}</pre>
+    <h4>環境変数の利用</h4>
+    <p>templateノードでは、次の構文を用いると環境変数にアクセスできます:</p>
+    <pre>私の好きな色は{{env.COLOUR}}です。</pre>
 </script>

test/nodes/core/function/15-change_spec.js

@@ -1717,6 +1717,24 @@ describe('change Node', function() {
                 changeNode1.receive({topic:{foo:{bar:1}}, payload:"String"});
             });
         });
+        it('moves the value of a message property object to itself', function(done) {
+            var flow = [{"id":"changeNode1","type":"change","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload","tot":"msg"}],"name":"changeNode","wires":[["helperNode1"]]},
+                        {id:"helperNode1", type:"helper", wires:[]}];
+            helper.load(changeNode, flow, function() {
+                var changeNode1 = helper.getNode("changeNode1");
+                var helperNode1 = helper.getNode("helperNode1");
+                helperNode1.on("input", function(msg) {
+                    try {
+                        msg.should.have.property('payload');
+                        msg.payload.should.equal("bar");
+                        done();
+                    } catch(err) {
+                        done(err);
+                    }
+                });
+                changeNode1.receive({payload:"bar"});
+            });
+        });
         it('moves the value of a message property object to a sub-property', function(done) {
             var flow = [{"id":"changeNode1","type":"change","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.foo","tot":"msg"}],"name":"changeNode","wires":[["helperNode1"]]},
                         {id:"helperNode1", type:"helper", wires:[]}];