Instead of showing a list of bug nubmers, such as:
 'This addresses bugs 123, 456, and 789',
this shows:
 'This addresses bugs 123, 456, and 789.

    http://bugs/123
    http://bugs/456
    http://bugs/789'

Even if a mail client does not automatically turn URLs to links in plain-text emails, the user can copy and paste the URL.
This avoids the headache of rewriting the email template to use HTML (which not all users may want, anyway).

The leading blank line was difficult to get rid of without making the template harder to read than it already is (and yes, the endfor is intentionally not on its own line). In order to keep the template semi-readable, I left the leading blank line there.

My internal site (Ubuntu Server 8.04 32-bit, python 2.5, django 1.0 beta 2) - emails went out with valid bug links and proper grammar.
Tested with issues referencing no bugs, 1 bug, 2 bugs, and 3 bugs.