Fix error detection for a non-existent global script.

lib/src/executable.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.
 
 library pub.executable;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:barback/barback.dart';
@@ skipping 87 matching lines @@
   var vmArgs = [];
 
   // Run in checked mode.
   if (checked) vmArgs.add("--checked");
 
   var executableUrl = await _executableUrl(
       entrypoint, package, executable, isGlobal: isGlobal, mode: mode);
 
   if (executableUrl == null) {
     var message = "Could not find ${log.bold(executable)}";
-    if (package != entrypoint.root.name) {
+    if (isGlobal || package != entrypoint.root.name) {
       message += " in package ${log.bold(package)}";
     }
     log.error("$message.");
     return exit_codes.NO_INPUT;
   }
 
   // If we're running an executable directly from the filesystem, make sure that
   // it knows where to load the packages. If it's a dependency's executable, for
   // example, it may not have the right packages directory itself.
   //
@@ skipping 165 matching lines @@
 Future<int> _runCachedExecutable(Entrypoint entrypoint, String snapshotPath,
     List<String> args, {bool checked: false}) {
   return runSnapshot(snapshotPath, args,
       packagesFile: entrypoint.packagesFile,
       checked: checked,
       recompile: () {
     log.fine("Precompiled executable is out of date.");
     return entrypoint.precompileExecutables();
   });
 }