* packages/debbugs/debbugs-gnu.el (subr-x): Require package.
(diff-hunk-file-names): Autoload function.
(top): Declare missing external variables. Move them up.
(debbugs-gnu-display-status, debbugs-gnu-usertags): Switching to
the buffer seems prettier than popping to the buffer.
(debbugs-gnu-usertags): Quote `highlight'.
(debbugs-gnu-change-checkin): Use `cl-subseq'.