## Summary
The nightly OSV artifact generation in `fleetdm/vulnerabilities` failed
over the weekend with:
```
fatal: error processing shallow info: 4
```
at `cmd/osv-processor/sync-and-detect-changes.sh` during:
```bash
git fetch --shallow-since="3 days ago" origin main
```
Root cause: `git fetch --shallow-since` errors out when the upstream
(`canonical/ubuntu-security-notices`) has zero commits newer than the
cutoff. Canonical didn't push anything over the weekend, so the 3-day
window returned empty and upload-pack produced an unusable shallow
response.
Fix:
- Fall back to `git fetch --depth=3` if `--shallow-since` still returns
empty, so the initial clone always succeeds.
Subsequent runs reuse the existing clone and take the other branch of
the script (plain `git fetch origin main`), which doesn't have this
failure mode.
Failing run:
https://github.com/fleetdm/vulnerabilities/actions/runs/24330589309/job/71035337352
## Test plan
- [x] Re-run the Ubuntu OSV artifact generation workflow; initial clone
succeeds regardless of upstream push frequency.
- [x] Manually exercise the cold-cache path locally: `rm -rf
ubuntu-security-notices &&
./cmd/osv-processor/sync-and-detect-changes.sh` — completes without
error.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved initial repository sync: if the primary shallow fetch returns
no commits, the process now falls back to a limited-depth fetch, warns
the user, and shows recent commit history before continuing. Downstream
change detection and existing behavior for already-cloned repos remain
unchanged.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Konstantin Sykulev <konst@sykulev.com>
