Rectirection while accessing via dns alias

If you use an alias to access to bitbucket, for example you've created hg.your-domain.com to point to bitbucket.org, now the site redirects to http://bitbucket.org or gives a 404 error.

This is a big problem to our developers, because we created a dns alias to have a more user friendly url and now we get this page:

Static

bitbucket.org - sans www.!