test_release tests against template.tpl, but actual Twisted releases should use the updated website-template.tpl that includes the current link and analytics code.
exarkun mentioned that website-template belongs in website repository ( lp:twisted-trac?) instead of the Twisted repository.
bin/admin/build-tarballs is hard-coded to use template.tpl, but this branch changed it to website-template.tpl, causing the test suite to fail.
So I suggest to add a template argument to the bin/admin/build-tarballs, if the argument is missing the default template.tpl will be used, included in the twisted source tree.
ReleaseProcess should be updated and explain how to obtain and use the website-template.tpl from the website repository.