grunt build (usemin) doesn't replace reference to "../app/bower_components/"

I run `grunt build` and the results are:

```
Running "clean:dist" (clean) task
Cleaning "dist/elements"...OK
Cleaning "dist/favicon.ico"...OK
Cleaning "dist/js"...OK
Cleaning "dist/robots.txt"...OK
Cleaning "dist/styles"...OK

Running "vulcanize:default" (vulcanize) task
OK

Running "useminPrepare:html" (useminPrepare) task
Going through app/index.html to update the config
Looking for build script HTML comment blocks

Found a block:



Updating config with the following assets:
- app/styles/main.css

Found a block:



Updating config with the following assets:
- app/bower_components/platform/platform.js

Configuration is now:

cssmin:
{ 'dist/styles/main.css': 'dist/styles/main.css' }

concat:
{ 'dist/styles/main.css': [ 'app/styles/main.css' ],
'dist/js/scripts.min.js': [ 'app/bower_components/platform/platform.js' ] }

uglify:
{ 'dist/js/scripts.min.js': 'dist/js/scripts.min.js' }

requirejs:
{}

Running "copy:dist" (copy) task
Created 1 directories, copied 5 files

Running "usemin:html" (usemin) task

Processing as HTML - dist/build.html
Update the HTML to reference our concat/min/revved script files
Update the HTML with the new css filenames
Update the HTML with the new img filenames
Update the HTML with data-main tags
Update the HTML with the data tags
Update the HTML with background imgs, case there is some inline style
Update the HTML with anchors images
Update the HTML with reference in input

Processing as HTML - dist/elements/performer-card.html
Update the HTML to reference our concat/min/revved script files
Update the HTML with the new css filenames
Update the HTML with the new img filenames
Update the HTML with data-main tags
Update the HTML with the data tags
Update the HTML with background imgs, case there is some inline style
Update the HTML with anchors images
Update the HTML with reference in input

Processing as HTML - dist/elements/performers-grid.html
Update the HTML to reference our concat/min/revved script files
Update the HTML with the new css filenames
Update the HTML with the new img filenames
Update the HTML with data-main tags
Update the HTML with the data tags
Update the HTML with background imgs, case there is some inline style
Update the HTML with anchors images
Update the HTML with reference in input

Running "usemin:css" (usemin) task

Done, without errors.
```

but the `build.html` file in `dist` still references `app/bower_components/` instead of the path set in the block.