getSkinFile doesn't return the proper URL to a ressource customized with XWikiSkinFileOverrideClass

How to reproduce

• in the XWiki.DefaultSkin, configured as the skin of the wiki
• add a new overridden template, for example print.css but works also for something like layoutExtraVars.vm
• get the URL of that resource, using the xwiki.getSkinFile() mechanism, for example using the following code:

  {{velocity}}
  $xwiki.getSkinFile('print.css', true)
  $xwiki.getSkinFile('layoutExtraVars.vm', true)
  {{/velocity}}
  

Expected result:

/xwiki/bin/skin/XWiki/DefaultSkin/print.css
/xwiki/bin/skin/XWiki/DefaultSkin/layoutExtraVars.vm

Actual result:

/xwiki/bin/skin/XWiki/DefaultSkin/content?cache-version=17.1
/xwiki/bin/skin/XWiki/DefaultSkin/content?cache-version=17.1

The URL of the actual result displays a "page not found" screen, doesn't return any content.

Note: for regular vms, even if the URL is broken the overwrite is actually taken into account.
However, for the overwrite of a css like print.css since the functioning of the overwrite is based on the URL to the CSS being correctly generated towards the skin file, it doesn't work.

Note: I did the test on a subwiki, not sure if it's relevant or not, but just in case.