Make pub generate .packages file.

lib/src/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 pub.entrypoint;
 
 import 'dart:async';
 
 import 'package:path/path.dart' as path;
 import 'package:barback/barback.dart';
 
 import 'barback/asset_environment.dart';
 import 'io.dart';
 import 'lock_file.dart';
 import 'log.dart' as log;
 import 'package.dart';
 import 'package_graph.dart';
+import 'package_locations.dart';
 import 'sdk.dart' as sdk;
 import 'solver/version_solver.dart';
 import 'source/cached.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 
 /// The context surrounding the root package pub is operating on.
 ///
 /// Pub operates over a directed graph of dependencies that starts at a root
 /// "entrypoint" package. This is typically the package where the current
@@ skipping 116 matching lines @@
     packageGraph.loadTransformerCache().clearIfOutdated(result.changedPackages);
 
     try {
       await precompileDependencies(changed: result.changedPackages);
       await precompileExecutables(changed: result.changedPackages);
     } catch (error, stackTrace) {
       // Just log exceptions here. Since the method is just about acquiring
       // dependencies, it shouldn't fail unless that fails.
       log.exception(error, stackTrace);
     }
+
+    writePackagesMap(_packageGraph);
   }
 
   /// Precompile any transformed dependencies of the entrypoint.
   ///
   /// If [changed] is passed, only dependencies whose contents might be changed
   /// if one of the given packages changes will be recompiled.
   Future precompileDependencies({Iterable<String> changed}) async {
     if (changed != null) changed = changed.toSet();
 
     var graph = await loadPackageGraph();
@@ skipping 391 matching lines @@
   /// If [packageSymlinks] is true, creates a symlink to the "packages"
   /// directory in [dir].
   ///
   /// Otherwise, deletes a "packages" directories in [dir] if one exists.
   void _linkOrDeleteSecondaryPackageDir(String dir) {
     var symlink = path.join(dir, 'packages');
     if (entryExists(symlink)) deleteEntry(symlink);
     if (_packageSymlinks) createSymlink(packagesDir, symlink, relative: true);
   }
 }