Fix for #1252: Using @partial-block twice in a template not possible

Fixes #1252
- This fix treats partial-blocks more like closures and uses the closure-context of
  the "invokePartial"-function to store the @partial-block for the partial.
- Adds a tes for the fix

lib/handlebars/runtime.js

@@ -210,12 +210,7 @@ export function wrapProgram(container, i, fn, data, declaredBlockParams, blockPa
 export function resolvePartial(partial, context, options) {
   if (!partial) {
     if (options.name === '@partial-block') {
-      let data = options.data;
-      while (data['partial-block'] === noop) {
-        data = data._parent;
-      }
-      partial = data['partial-block'];
-      data['partial-block'] = noop;
+      partial = options.data['partial-block'];
     } else {
       partial = options.partials[options.name];
     }
@@ -228,6 +223,8 @@ export function resolvePartial(partial, context, options) {
 }
 
 export function invokePartial(partial, context, options) {
+  // Use the current closure context to save the partial-block if this partial
+  const currentPartialBlock = options.data && options.data['partial-block'];
   options.partial = true;
   if (options.ids) {
     options.data.contextPath = options.ids[0] || options.data.contextPath;
@@ -236,10 +233,17 @@ export function invokePartial(partial, context, options) {
   let partialBlock;
   if (options.fn && options.fn !== noop) {
     options.data = createFrame(options.data);
-    partialBlock = options.data['partial-block'] = options.fn;
-
-    if (partialBlock.partials) {
-      options.partials = Utils.extend({}, options.partials, partialBlock.partials);
+    // Wrapper function to get access to currentPartialBlock from the closure
+    let fn = options.fn;
+    partialBlock = options.data['partial-block'] = function partialBlockWrapper(context, options) {
+      // Restore the partial-block from the closure for the execution of the block
+      // i.e. the part inside the block of the partial call.
+      options.data = createFrame(options.data);
+      options.data['partial-block'] = currentPartialBlock;
+      return fn(context, options);
+    };
+    if (fn.partials) {
+      options.partials = Utils.extend({}, options.partials, fn.partials);
     }
   }
 

spec/partials.js

@@ -249,6 +249,13 @@ describe('partials', function() {
         true,
         'success');
     });
+    it('should be able to render the partial-block twice', function() {
+      shouldCompileToWithPartials(
+          '{{#> dude}}success{{/dude}}',
+          [{}, {}, {dude: '{{> @partial-block }} {{> @partial-block }}'}],
+          true,
+          'success success');
+    });
     it('should render block from partial with context', function() {
       shouldCompileToWithPartials(
         '{{#> dude}}{{value}}{{/dude}}',