When multiple releases use the same OCI chart (e.g., same chart different
values), workers in PrepareCharts would deadlock:
1. Worker 1 acquires lock for chart/path, downloads, adds to cache
2. Worker 2 finds chart in cache, tries to acquire lock on same path
3. Worker 2 blocks waiting for Worker 1's lock
4. Collector waits for Worker 2's result
5. Worker 1's lock held until PrepareCharts finishes -> deadlock
The fix: when using the in-memory chart cache (which means another worker
in the same process already downloaded the chart), don't acquire another
lock. This is safe because:
- The in-memory cache is only used within a single helmfile process
- The tempDir cleanup is deferred until after helm callback completes
- Cross-process coordination is still handled by file locks during downloads
This fixes the "signal: killed" test failures in CI for:
- oci_chart_pull_direct
- oci_chart_pull_once
- oci_chart_pull_once2
Signed-off-by: Aditya Menon <amenon@canarytechnologies.com>
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