fix: the manifest paths should not include the root

Author: hansl

lib/broccoli/service-worker-manifest.js

@@ -57,13 +57,15 @@ class DiffingSWManifest extends Plugin {
     var files = Object.keys(manifest).sort();
     var bundleHash = this.computeBundleHash(files, manifest);
     var contents = files
-      .map((file) => `# sw.file.hash: ${this.computeFileHash(file)}\n${path.sep}${file}`)
+      .map((file) => {
+        return `# sw.file.hash: ${this.computeFileHash(file)}\n`
+             + `${path.sep}${path.relative(this.inputPaths[0], file)}`;
+      })
       .join('\n');
-    return `CACHE MANIFEST
-# sw.bundle: ng-cli
-# sw.version: ${bundleHash}
-${contents}
-`;
+    return 'CACHE MANIFEST\n'
+         + '# sw.bundle: ng-cli\n'
+         + `# sw.version: ${bundleHash}\n`
+         + `${contents}\n`;
   }
 
   // Read the manifest from the cache and split it out into a dict of files to hashes.