Fix for legacy manifest file

src/api/build.ts

@@ -79,7 +79,8 @@ async function execute(emitter: EventEmitter, opts: Opts, dirs: Dirs) {
 			// TODO duration/warnings
 			result: client_result
 		});
-
+		
+		client_result.to_json(manifest_data, dirs);
 		build_info.legacy_assets = client_result.assets;
 		delete process.env.SAPPER_LEGACY_BUILD;
 	}

src/core/create_compilers/extract_css.ts

@@ -170,6 +170,7 @@ export default function extract_css(client_result: CompileResult, components: Pa
 	}
 
 	const main = client_result.assets.main;
+	if (process.env.SAPPER_LEGACY_BUILD) main = `legacy/${main}`;
 	const entry = fs.readFileSync(`${dirs.dest}/client/${main}`, 'utf-8');
 
 	const replacements = new Map();