pub fn cleanup_stale_old_binary()Expand description
Best-effort cleanup of a leftover <current_exe>.old from a prior
Windows self-update.
On Windows, manual or recovery scenarios may leave a seshat.exe.old
next to the running seshat.exe (the happy-path self_replace::self_replace
flow already schedules its own relocated-binary deletion via the crate’s
.__selfdelete__.exe helper, so this is purely defensive). Errors are
silently dropped — cleanup must never fail the user’s command.
On Unix this is a no-op: atomic rename(2) semantics in replace_binary
never leave a .old file behind, so there is nothing to probe for.