- --chmod no longer implies --preserve-perms; repeated --chmod options
accumulate, and D/F/X selectors plus s/t special bits are supported with
rsync's exact parse_chmod/tweak_mode semantics.
- Stop masking group/other write and setuid/setgid/sticky: -p copies the
source mode exactly, no-p new entries use source&~umask, directories keep
setgid/sticky, and special nodes follow the same rules.
- Apply ownership before mode on the fd path so a chown cannot clear the
setuid/setgid bits -p just restored (rsync order).
- Update unit and integration tests, including differential checks against
rsync 3.4.1.