Got an unexpected error in `pub build` with `--mode=debug` flag.md

I got dart-material-design-lite-site codes.

$ git clone --depth 1 https://github.com/MikeMitterer/dart-material-design-lite-site.git
$ cd dart-material-design-lite-site

and edit pubspec.yaml, switch mdl to any:

mdl: any

then pub get:

$ pub get

and just pub build. This is OK. No problems:

$ pub build

But in this case, got an error with --mode=debug flag:

$ pub build --mode=debug
...
[Info from Dart2JS]:
Took 0:00:12.583303 to compile mdl_site|web/main.dart.
Could not find asset mdl|lib/_templates/android/manifest.yaml.
package:pub/src/barback/pub_package_provider.dart 112  PubPackageProvider._assertExists
package:pub/src/barback/pub_package_provider.dart 106  PubPackageProvider.getAsset.<async>
This is an unexpected error. Please run

    pub --trace build --mode=debug

and include the results in a bug report on http://dartbug.com/new.

---

My environments:

• mdl 1.15.1
• Dart VM version: 1.13.2 (Tue Jan 5 06:36:44 2016) on "macos_x64"
• Pub 1.13.2
• barback 0.15.2+7

mdl 22459eb(1.15.1+) on Jan 22, 2016 is no problems.