Make pub's binstubs resilient to changes in snapshot format.

sdk/lib/_internal/pub_generated/test/cache/repair/handles_corrupted_binstub_test.dart

Index: sdk/lib/_internal/pub_generated/test/cache/repair/handles_corrupted_binstub_test.dart
diff --git a/sdk/lib/_internal/pub_generated/test/global/binstubs/does_not_warn_if_no_executables_test.dart b/sdk/lib/_internal/pub_generated/test/cache/repair/handles_corrupted_binstub_test.dart
similarity index 62%
copy from sdk/lib/_internal/pub_generated/test/global/binstubs/does_not_warn_if_no_executables_test.dart
copy to sdk/lib/_internal/pub_generated/test/cache/repair/handles_corrupted_binstub_test.dart
index ac6348a1d6726edfb3817ba9869c5a691470595f..51c4deb2227f801bb21b559e6cc19f6c8f52d0cd 100644
--- a/sdk/lib/_internal/pub_generated/test/global/binstubs/does_not_warn_if_no_executables_test.dart
+++ b/sdk/lib/_internal/pub_generated/test/cache/repair/handles_corrupted_binstub_test.dart
@@ -2,9 +2,10 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+library pub_tests;
+
 import 'dart:io';
 
-import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../descriptor.dart' as d;
@@ -12,17 +13,23 @@ import '../../test_pub.dart';
 
 main() {
   initConfig();
-  integration("does not warn if the package has no executables", () {
+  integration('handles a corrupted binstub script', () {
     servePackages((builder) {
       builder.serve(
           "foo",
           "1.0.0",
           contents: [
-              d.dir("bin", [d.file("script.dart", "main(args) => print('ok \$args');")])]);
+              d.dir("bin", [d.file("script.dart", "main(args) => print('ok');")])]);
     });
 
+    schedulePub(args: ["global", "activate", "foo"]);
+
+    d.dir(
+        cachePath,
+        [d.dir('bin', [d.file(binStubName('script'), 'junk')])]).create();
+
     schedulePub(
-        args: ["global", "activate", "foo"],
-        output: isNot(contains("is not on your path")));
+        args: ["cache", "repair"],
+        error: contains('Error reading binstub for "script":'));
   });
 }