Show better error messages in network failures.

utils/pub/package.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 package;
 
 import 'io.dart';
 import 'pubspec.dart';
 import 'source.dart';
 import 'source_registry.dart';
@@ skipping 119 matching lines @@
   bool operator ==(other) {
     if (other is! PackageId) return false;
     // TODO(rnystrom): We're assuming here the name/version/source tuple is
     // enough to uniquely identify the package and that we don't need to delve
     // into the description.
     return other.name == name &&
            other.source.name == source.name &&
            other.version == version;
   }
 
-  String toString() => "$name $version from ${source.name}";
+  String toString() {
+    if (source.isDefault) return "$name $version";
+    return "$name $version from $source";
+  }
 
   int compareTo(Comparable other) {
     if (other is! PackageId) throw new ArgumentError(other);
 
     var sourceComp = source.name.compareTo(other.source.name);
     if (sourceComp != 0) return sourceComp;
 
     var nameComp = name.compareTo(other.name);
     if (nameComp != 0) return nameComp;
 
@@ skipping 67 matching lines @@
 
 class PubspecNameMismatchException implements Exception {
   final String expectedName;
   final String actualName;
 
   PubspecNameMismatchException(this.expectedName, this.actualName);
 
   String toString() => 'The name you specified for your dependency, '
     '"$expectedName", doesn\'t match the name "$actualName" in its pubspec.';
 }