How can you force a stylesheet reload in Drupal7? This is about that old trick of tacking a fake query argument onto the URL of a stylesheet (e.g., &lt;link rel="stylesheet" type="text/css" href="http://www.example.com/site.css?v=123"&gt;) so that, when you change the stylesheet, it'll be reloaded by the users' browsers, since it looks like a URL that's not in the browser's cache.  

So, the question: How can you do this in D7 where the stylesheets are specified in the .info files?  I tried adding a query arg onto the entry in my site's info file -- stylesheets[all][] = site.css?v=123 but without any luck (the page rendering got very unhappy).  Any ideas?
You can do this with drush

$ drush help cache-clear
Clear a specific cache, or all drupal caches.

Arguments:
 type                                      The particular cache to clear. Omit 
                                           this argument to choose from        
                                           available caches.                   


Aliases: cc


So you can do

drush cc css-js


and this will rescan the cached CSS and JS files, nuke them if they are stale, and generate a new key that gets appended to CSS and JS URLs.