Fix duplicated content due to symlinks

src/Bundler.js

@@ -363,15 +363,19 @@ class Bundler extends EventEmitter {
   }
 
   async resolveAsset(name, parent) {
-    let {path} = await this.resolver.resolve(name, parent);
-    return this.getLoadedAsset(path);
+    let {path, realpath} = await this.resolver.resolve(name, parent);
+    return this.getLoadedAsset(path, realpath);
   }
 
-  getLoadedAsset(path) {
+  getLoadedAsset(path, realpath) {
     if (this.loadedAssets.has(path)) {
       return this.loadedAssets.get(path);
     }
 
+    if (this.loadedAssets.has(realpath)) {
+      return this.loadedAssets.get(realpath);
+    }
+
     let asset = this.parser.getAsset(path, this.options);
     this.loadedAssets.set(path, asset);
 

src/Resolver.js

@@ -292,7 +292,8 @@ class Resolver {
     // Try all supported extensions
     for (let f of this.expandFile(file, extensions, pkg)) {
       if (await this.isFile(f)) {
-        return {path: f, pkg};
+        let realpath = await fs.realpath(f);
+        return {path: f, realpath, pkg};
       }
     }
   }

test/integration/resolver/barsym.js

@@ -0,0 +1 @@
+./bar.js

test/resolver.js

@@ -78,6 +78,17 @@ describe('resolver', function() {
       );
       assert.equal(resolved.pkg.name, 'foo');
     });
+
+    it('should resolve a symlinked path and provide the realpath', async function() {
+      let resolved = await resolver.resolve(
+        './barsym',
+        path.join(rootDir, 'foo.js')
+      );
+
+      assert.equal(resolved.path, path.join(rootDir, 'barsym.js'));
+      assert.equal(resolved.realpath, path.join(rootDir, 'bar.js'));
+      assert.equal(resolved.pkg.name, 'resolver');
+    });
   });
 
   describe('builtins', function() {