Tour application does not work on subwikis

Tested on XWiki 7.4.2, on design.xwiki.org and will affect any instance below 7.4.3.

Problem: the webjar URL is not correctly generated, pointing to main wiki.
For example this URL was generated:

http://design.xwiki.org/xwiki/webjars/bootstrap-tour/0.10.2-1/js/bootstrap-tour.min.js?r=1

instead of

http://...&wiki=design

Since 7.4M2+ (1) a wiki parameter is needed in webjar script service.
Before 7.4M2 there is no solution for subwikis.

(1) http://extensions.xwiki.org/xwiki/bin/view/Extension/WebJars+Integration#HURLFormat