/usr/share/mercurial/templates/paper/ is in mercurial-common 4.0-1+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/mercurial/templates/paper/bookmarks.tmpl
/usr/share/mercurial/templates/paper/branches.tmpl
/usr/share/mercurial/templates/paper/changeset.tmpl
/usr/share/mercurial/templates/paper/diffstat.tmpl
/usr/share/mercurial/templates/paper/error.tmpl
/usr/share/mercurial/templates/paper/fileannotate.tmpl
/usr/share/mercurial/templates/paper/filecomparison.tmpl
/usr/share/mercurial/templates/paper/filediff.tmpl
/usr/share/mercurial/templates/paper/filelog.tmpl
/usr/share/mercurial/templates/paper/filelogentry.tmpl
/usr/share/mercurial/templates/paper/filerevision.tmpl
/usr/share/mercurial/templates/paper/footer.tmpl
/usr/share/mercurial/templates/paper/graph.tmpl
/usr/share/mercurial/templates/paper/header.tmpl
/usr/share/mercurial/templates/paper/help.tmpl
/usr/share/mercurial/templates/paper/helptopics.tmpl
/usr/share/mercurial/templates/paper/index.tmpl
/usr/share/mercurial/templates/paper/manifest.tmpl
/usr/share/mercurial/templates/paper/map
/usr/share/mercurial/templates/paper/notfound.tmpl
/usr/share/mercurial/templates/paper/search.tmpl
/usr/share/mercurial/templates/paper/shortlog.tmpl
/usr/share/mercurial/templates/paper/shortlogentry.tmpl
/usr/share/mercurial/templates/paper/tags.tmpl