Outputs my-app.html despite already bundling it in index.html

[tony19]

Description

The --bundle flag bundles src/my-app.html in index.html, but it also copies src/my-app.html to the output folder. Interestingly, the master branch (3517653) does even more than 0.18.0-pre.10 and copies other already bundled files. Here's a demo repo: https://github.com/tony19-sandbox/polymer-build-issue-142

Versions & Environment

• polymer-build: 0.8.1
• polymer-cli: 0.18.0-pre.10
• node: 7.6.0
• Operating System: macOS Sierra 10.12

Steps to Reproduce

1. Create application project with polymer-cli.
2. CD into project directory.
3. Create polymer.json with these contents:

{
  "builds": [
    {
      "bundle": true,
      "js": {
        "minify": true,
        "compile": true
      },
      "css": {
        "minify": true
      },
      "html": {
        "minify": true
      }
    }
  ]
}

4. Run polymer build

Expected Results

• index.html includes contents of src/my-app.html
• Output directory does not contain src/my-app.html

Actual Results

• index.html includes contents of src/my-app.html ✅
• Output directory contains src/my-app.html ❌