Hi,

I think bug-reference.el is missing a "(provide 'bug-reference)".

And I would suggest changing `bug-reference-bug-regexp' from a constant
to a variable and marking it as safe-local-variable for
`string-or-null-p'. This way it is possible to bind it in .dir-locals.el
like it is already possible to bind `bug-reference-url-format'.

Kind regards,
Arne