Pub can't serve main.dart from nested folder when using DDC

[lexaknyazev]

Dart SDK 1.25.0-dev.7.0

1. Create a bare-bones web app from template.
2. Move main.dart from web to web/scripts, update reference in HTML.
3. Run pub serve with Dart2JS, open webpage. Everything works fine:

Loading source assets...
Loading dart_to_js_script_rewriter transformers...
Serving pub_bug web on http://localhost:8080
Build completed successfully
[web] GET Served 3 assets.
[Info from Dart2JS]:
Compiling pub_bug|web/scripts/main.dart...
[Info from Dart2JS]:
Took 0:00:03.435261 to compile pub_bug|web/scripts/main.dart.
Build completed successfully
[web] GET Served 2 assets.

4. Re-run with DDC: pub serve --web-compiler=dartdevc, open webpage.

Loading source assets...
Loading dart_to_js_script_rewriter transformers...
Serving pub_bug web on http://localhost:8080
Build completed successfully
[web] GET Served 3 assets.
[web] GET Served 4 assets.
[web] GET main.dart.bootstrap.js => Could not find asset pub_bug|web/main.dart.

5. Browser's JS console contains:

main.dart.bootstrap.js Failed to load resource: the server responded with a status of 404 (Not Found)
require.js:143 Uncaught Error: Script error for "main.dart.bootstrap"
http://requirejs.org/docs/errors.html#scripterror
    at makeError (require.js:168)
    at HTMLScriptElement.onScriptError (require.js:1738)

[vsmenon]

@jakemac53 @natebosch

[jakemac53]

While you wait for this to get merged into the sdk you can test it out by adding the following to your pubspec.yaml:

dev_dependencies:
  pub:
    git: https://github.com/dart-lang/pub.git

And then running pub run pub serve --web-compiler=dartdevc