/usr/share/mercurial/templates/raw/changelog.tmpl is in mercurial-common 4.5.3-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | {header}
# HG changelog
# Node ID {node}
{entries%changelogentry}
|