Install barback from a hosted source in all tests.

test/global/run/mode_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 '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 const TRANSFORMER = """
 import 'dart:async';
 
@@ skipping 11 matching lines @@
         new AssetId(transform.primaryInput.id.package, "bin/script.dart"),
         "void main() => print('\${_settings.mode.name}');"));
   }
 }
 """;
 
 main() {
   integration('runs a script in an activated package with customizable modes',
       () {
     servePackages((builder) {
-      builder.serveRepoPackage("barback");
+      builder.serveRealPackage("barback");
 
       builder.serve("foo", "1.0.0",
           deps: {"barback": "any"},
           pubspec: {"transformers": ["foo/src/transformer"]},
           contents: [
         d.dir("lib", [d.dir("src", [
           d.file("transformer.dart", TRANSFORMER),
           d.file("primary.in", "")
         ])])
       ]);
     });
 
     schedulePub(args: ["global", "activate", "foo"]);
 
     // By default it should run in release mode.
     var pub = pubRun(global: true, args: ["foo:script"]);
     pub.stdout.expect("release");
     pub.shouldExit();
 
     // A custom mode should be specifiable.
     pub = pubRun(global: true, args: ["--mode", "custom-mode", "foo:script"]);
     pub.stdout.expect("custom-mode");
     pub.shouldExit();
   });
 }