Zombie tenants are not pruned #8485
Description
Thanos, Prometheus and Golang version used:
A recent thanos version
Object Storage Provider:
What happened:
We found that in rare cases tenants are never pruned because head.MaxTime() is math.MinInt64, and is skipped here. We checked prometheus tsdb active time series is 0 so the tenant should be pruned at some point.
What you expected to happen:
Zombie tenants are pruned eventually.
How to reproduce it (as minimally and precisely as possible):
Didn't know what triggered this, but it appears that the tenant was created but never got samples written to it.
Full logs to relevant components:
Anything else we need to know: