PACKAGING FIX: rsync daemon default group on stock Ubuntu/Debian (ELSR-8050)
the daemon's compile-time NOBODY_GROUP was resolved to "nobody" by the
focal build chroot's /etc/group, but stock Ubuntu/Debian have only
"nogroup", so daemon modules with no explicit gid were rejected with
"@ERROR: invalid gid nobody" (test_daemon / ELSR-8050)
debian/rules: build with rsync's own --with-nobody-group=nogroup
configure option so the compile-time NOBODY_GROUP default is baked as
"nogroup" regardless of the build chroot, matching the stock
Ubuntu/Debian rsync build (fixes modules with no explicit gid)
debian/patches/rsync-daemon-nobody-group-fallback.patch: in the daemon's
add_a_group() resolve a "nobody" group to "nogroup" at runtime when the
host has no "nobody" group, so a module that explicitly sets
"gid = nobody" is also honoured on stock Ubuntu/Debian instead of being
rejected with "@ERROR: invalid gid nobody"; any other unresolvable group
is still rejected