* filer.backup: retry a failed checkpoint read instead of replaying from the epoch
Fixes#12035
* test: reset sink.local.directory in backup offset test cleanup
The new test sets sink.local.directory on the shared viper but only
reset the enabled flag, leaking a key that points at a deleted
t.TempDir() to later tests in the package.
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* test: cover the retried attempt re-reading the checkpoint
The fake filer now fails only its first KvGet, and the test runs a
second doFilerBackup attempt asserting the checkpoint is re-read and
the attempt proceeds past the offset stage. LookupDirectoryEntry is
stubbed so the SSE-S3 KEK probe returns a miss instead of retrying
10x2s.
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---------
Co-authored-by: user.email <chrislusf@users.noreply.github.com>
Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
