True when a download for this exact repoId is currently "active" in this
process's tracker (used by the Hub's POST /api/hub/download to refuse a
duplicate kick-off — same repoId, still running — rather than starting a
second writer that would race the first on the same blob lockfile).
True when a download for this exact repoId is currently "active" in this process's tracker (used by the Hub's POST /api/hub/download to refuse a duplicate kick-off — same repoId, still running — rather than starting a second writer that would race the first on the same blob lockfile).