bug fix.

extensions/composer/Installer.php

@@ -95,7 +95,7 @@ class Installer extends LibraryInstaller
 				}
 				$path = $fs->normalizePath($path);
 				if (strpos($path . '/', $vendorDir . '/') === 0) {
-					return ["@$name" => '<vendor-dir>/' . substr($path, strlen($vendorDir)) . '/' . $name];
+					return ["@$name" => '<vendor-dir>' . substr($path, strlen($vendorDir)) . '/' . $name];
 				} else {
 					return ["@$name" => $path . '/' . $name];
 				}

extensions/composer/Plugin.php

@@ -29,7 +29,7 @@ class Plugin implements PluginInterface
 		$file = rtrim($composer->getConfig()->get('vendor-dir'), '/') . '/yiisoft/extensions.php';
 		if (!is_file($file)) {
 			@mkdir(dirname($file));
-			file_put_contents($file, "<?php\nreturn [];\n");
+			file_put_contents($file, "<?php\n\nreturn [];\n");
 		}
 	}
 }