The easiest way might be to make a fresh install of OpenACS, then go to the "install applications" administration page, and click on bugtracker.
That will bring you to a page listing all of the packages that bugtracker depends on that the package manager must load (it's a confirmation page, essentially).
You can also find the first-order dependencies in the bugtracker.info XML file in the package itself. However this won't tell you what packages those packages in turn depend upon.
One package I know it depends on is the workflow package...
