Fix various pub issues.

lib/src/pubspec.dart

Index: lib/src/pubspec.dart
diff --git a/lib/src/pubspec.dart b/lib/src/pubspec.dart
index 13cce16e8583318ce3f61ca8121b01cc9d44a891..19bd769fcef94b3cfe96bb9cd7ff758996080cab 100644
--- a/lib/src/pubspec.dart
+++ b/lib/src/pubspec.dart
@@ -312,7 +312,10 @@ class Pubspec {
     var pubspecUri = path.toUri(pubspecPath);
     if (!fileExists(pubspecPath)) {
       throw new FileException(
-          'Could not find a file named "pubspec.yaml" in "$packageDir".',
+          // Make the package dir absolute because for the entrypoint it'll just
+          // be ".", which may be confusing.
+          'Could not find a file named "pubspec.yaml" in '
+              '"${path.normalize(path.absolute(packageDir))}".',
           pubspecPath);
     }