-4. `ssh` in to `tar xf --no-same-owner` (lands at `~/<repo-dirname>`). The
- flag matters: GNU `tar` as root defaults to `--same-owner`, which would
- restore the *workstation's* numeric UID onto files under `/root`; that
- silent mismatch would otherwise make any later root-run `git` operation
- against that tree refuse it as "dubious ownership". Then `ssh -t`
- (pseudo-tty, since the script ends prompting for a password) to run
- `./${RELPATH_SETUP_SCRIPT}`.
+4. `ssh` in to `tar xf -C /opt --no-same-owner` (lands at
+ `${PATH_REMOTE_REPO}`), then remove the uploaded tar. The flag matters:
+ GNU `tar` as root defaults to `--same-owner`, which would restore the
+ *workstation's* numeric UID onto the files; that silent mismatch would
+ otherwise make any later root-run `git` operation against that tree
+ refuse it as "dubious ownership". (Root-owned, the tree is still readable
+ by the user as long as the checkout's modes are the usual 644/755, which
+ GNU `tar` as root preserves.) Then `ssh -t` (pseudo-tty, since the script
+ ends prompting for a password) to run `${PATH_SETUP_SCRIPT}`.
+
+Not rerunnable once `start_root_server.sh` got as far as disabling root SSH;
+before that (e.g. an `apt-get` failure), a rerun just unpacks over the
+existing tree.