LESS Cache is not cleared on the main wiki when a subwiki color theme is saved

When you have a subwiki using a skin stored in the main wiki and a color theme stored in that subwiki, the LESS cache of the couple (main wiki skin/subwiki color theme) is not cleared when the color theme is saved.

For example,
make some changes to the buttons in
http://extensions.xwiki.org/xwiki/bin/view/ColorThemes/ExtensionsCT
If you want to see the changes applied, you need to go to the main wiki and save the ColorTheme there http://www.xwiki.org/xwiki/bin/edit/ColorThemes/Blueberry