An empty, comments-only or whitespace-only users file is not a parse error,
so it walked straight through the requirement #51 built: pre-flight passed,
apply converged nothing, and the box came up root-only — the exact outcome
--no-users exists to make explicit, reached by the flag added to guarantee
the opposite. `--users ./empty` and `--no-users` produced the identical box
and only one of them said so.
Catch the zero-user parse in bootstrap's pre-flight, where the file is
already parsed for validation and before apt, the hostname change, or a
spent pre-auth key. The refusal names --no-users: the root-only box is
reachable, it just has to be asked for out loud.
Deliberately narrow. This is bootstrap's contract, not the parser's and not
apply's: zero users is a legal file, and a standalone `rig users apply`
against an emptied file is a real de-provisioning operation that must stay
possible. Negative-grep tests pin both.
Closes#57
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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