/usr/share/mercurial/help/ is in mercurial-common 2.0.2-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/mercurial/help/config.txt
/usr/share/mercurial/help/dates.txt
/usr/share/mercurial/help/diffs.txt
/usr/share/mercurial/help/environment.txt
/usr/share/mercurial/help/extensions.txt
/usr/share/mercurial/help/filesets.txt
/usr/share/mercurial/help/glossary.txt
/usr/share/mercurial/help/hgignore.txt
/usr/share/mercurial/help/hgweb.txt
/usr/share/mercurial/help/merge-tools.txt
/usr/share/mercurial/help/multirevs.txt
/usr/share/mercurial/help/patterns.txt
/usr/share/mercurial/help/revisions.txt
/usr/share/mercurial/help/revsets.txt
/usr/share/mercurial/help/subrepos.txt
/usr/share/mercurial/help/templates.txt
/usr/share/mercurial/help/urls.txt