Url rewrite does not work for assets inherited from plugin

[Pawel]

Replication steps (tested with Grails 3.1.4)

1. Create a new Grails plugin and copy font-awesome folders into grails-app/assets/vendor
2. Create a new Grails app and add the following line to application.css:
   *= require font-awesome/css/font-awesome.css
3. Add inline plugin dependency to your app (as described in Grails user guide)
4. Create application WAR file

Result: In build output files font-awesome.css is included to application.css, but all url entries from font-awesome.css are unchanged (thus not pointing to correct font files), e.g.

@font-face {
  font-family: 'Glyphicons Halflings';
  src: url('../fonts/glyphicons-halflings-regular.eot');
  ...

should be changed to:

@font-face {
  font-family: 'Glyphicons Halflings';
  src: url('font-awesome/fonts/glyphicons-halflings-regular.eot');
  ...

[David Estes]

should work now