Use relative symlinks for self links and secondary "packages" dirs.

utils/pub/entrypoint.dart

 // Copyright (c) 2012, 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 entrypoint;
 
 import 'dart:async';
 
 import '../../pkg/path/lib/path.dart' as path;
 
@@ skipping 214 matching lines @@
 
   /// Installs a self-referential symlink in the `packages` directory that will
   /// allow a package to import its own files using `package:`.
   Future _installSelfReference(_) {
     return defer(() {
       var linkPath = path.join(packagesDir, root.name);
       // Create the symlink if it doesn't exist.
       if (entryExists(linkPath)) return;
       ensureDir(packagesDir);
       return createPackageSymlink(root.name, root.dir, linkPath,
-          isSelfLink: true);
+          isSelfLink: true, relative: true);
     });
   }
 
   /// If `bin/`, `test/`, or `example/` directories exist, symlink `packages/`
   /// into them so that their entrypoints can be run. Do the same for any
   /// subdirectories of `test/` and `example/`.
   Future _linkSecondaryPackageDirs(_) {
     var binDir = path.join(root.dir, 'bin');
     var exampleDir = path.join(root.dir, 'example');
     var testDir = path.join(root.dir, 'test');
@@ skipping 43 matching lines @@
         });
       }).toList());
     }).then(flatten);
   }
 
   /// Creates a symlink to the `packages` directory in [dir] if none exists.
   Future _linkSecondaryPackageDir(String dir) {
     return defer(() {
       var symlink = path.join(dir, 'packages');
       if (entryExists(symlink)) return;
-      return createSymlink(packagesDir, symlink);
+      return createSymlink(packagesDir, symlink, relative: true);
     });
   }
 }