When using a custom CNAME with bitbucket, forks links are not correct (BB-685))

When someone hosts his project on bitbucket.org and associates it with a custom CNAME, he can link to his projet with an url like http://his.domain.tld/username/project

If the project is forked, then forks will be indicated in the forks/queues page but links to them will be incorrect, using the same CNAME instead of the bitbucket.org domain.

You can see an example with the django-authopenid using the url http://hg.e-engura.org/django-authopenid/descendants/

Maybe this problem appears in other pages.