Django's URLField is fairly strict in the kinds of URLs it allows. For example, it fails to allow domain-less (internal) hostnames; see http://code.djangoproject.com/ticket/7969. Based on django tickets, it also prevents some other useful real-world URLs.

Since the bug tracker URL is controlled by the administrator, and internal sites may face working with legacy system integration, I propose removing the URL validation by switching to CharField.

Not covered in this patch is altering django's source to fix url_re in Django's source (url_re in django/forms/fields.py line 523).

None (I modified the database directly, which worked for my internal installation's needs)