Fix broken pub tests.

sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart

Index: sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart
diff --git a/sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart b/sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart
index 9e60b5f7790e88b3d365cc37e645e0d02c10310d..d1bacfcf030bab9f3a2c39e631f9b41de0671435 100644
--- a/sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart
+++ b/sdk/lib/_internal/pub/test/cache/add/package_not_found_test.dart
@@ -4,6 +4,7 @@
 
 library pub_tests;
 
+import '../../../lib/src/exit_codes.dart' as exit_codes;
 import '../../test_pub.dart';
 
 main() {
@@ -13,6 +14,6 @@ main() {
 
     schedulePub(args: ["cache", "add", "foo"],
         error: new RegExp(r"Could not find package foo at http://.*"),
-        exitCode: 1);
+        exitCode: exit_codes.UNAVAILABLE);
   });
 }