/usr/lib/tcltk/rivet2.3/rivet-tcl/ is in libapache2-mod-rivet 2.3.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/tcltk/rivet2.3/rivet-tcl/catch.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/cookie.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/debug.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/html.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/http_accept.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/import_keyvalue_pairs.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/import_switch_args.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/lempty.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/lmatch.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/load_cookies.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/load_response.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/parray.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/parray_table.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/putsnnl.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/random.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/read_file.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/redirect.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/rivet_command_document.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/tclIndex
/usr/lib/tcltk/rivet2.3/rivet-tcl/try.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/url_query.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/wrap.tcl
/usr/lib/tcltk/rivet2.3/rivet-tcl/xml.tcl