The first deployment of any routed target could never succeed, and wedged
itself permanently on the way down.
The route preflight bind-mounts its candidate over config_path to run
`nginx -t` in a private mount namespace. When that path does not exist yet,
systemd materializes the mount point and leaves an empty file on the host.
Read as content, that made the baseline "change" during validation, failing
the transaction -- and every retry then saw a zero-length fragment where the
transaction expected none and reported an unadmitted incumbent, which no
amount of retrying could clear.
A fragment with no bytes grants no route, so it is now read as absence. That
makes the preflight idempotent whether or not systemd materialized the mount
point, and lets a first deployment retry cleanly.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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