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

sdk/lib/_internal/pub/test/global/activate/outdated_binstub_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+import 'dart:io';
+import 'dart:async';
+
+import 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_process.dart';
+import 'package:scheduled_test/scheduled_stream.dart';
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+const _OUTDATED_BINSTUB = """
+#!/usr/bin/env sh
+# This file was created by pub v0.1.2-3.
+# Package: foo
+# Version: 1.0.0
+# Executable: foo-script
+# Script: script
+dart "/path/to/.pub-cache/global_packages/foo/bin/script.dart.snapshot" "\$@"
+""";
+
+main() {
+  initConfig();
+  integration("an outdated binstub is replaced", () {
+    servePackages((builder) {
+      builder.serve("foo", "1.0.0", pubspec: {
+        "executables": {
+          "foo-script": "script"
+        }
+      }, contents: [
+        d.dir("bin", [
+          d.file("script.dart", "main(args) => print('ok \$args');")
+        ])
+      ]);
+    });
+
+    schedulePub(args: ["global", "activate", "foo"]);
+
+    d.dir(cachePath, [
+      d.dir('bin', [
+        d.file(binStubName('foo-script'), _OUTDATED_BINSTUB)
+      ])
+    ]).create();
+
+    schedulePub(args: ["global", "activate", "foo"]);
+
+    d.dir(cachePath, [
+      d.dir('bin', [
+        // 255 is the VM's exit code upon seeing an out-of-date snapshot.
+        d.matcherFile(binStubName('foo-script'), contains("255"))
+      ])
+    ]).validate();
+  });
+}