Flaky Test: TestKVStore/ConcurrentUpdate

```
--- FAIL: TestKVStore (1.07s)
--- PASS: TestKVStore/Get (0.00s)
--- PASS: TestKVStore/Get/get_key (0.00s)
--- PASS: TestKVStore/Get/get_missing_key (0.00s)
--- PASS: TestKVStore/Put (0.00s)
--- PASS: TestKVStore/Put/put_pair (0.00s)
--- PASS: TestKVStore/Delete (0.01s)
--- PASS: TestKVStore/Delete/delete_key (0.01s)
--- PASS: TestKVStore/Cursor (0.01s)
--- PASS: TestKVStore/Cursor/basic_cursor (0.01s)
--- PASS: TestKVStore/View (0.02s)
--- PASS: TestKVStore/View/basic_view (0.01s)
--- PASS: TestKVStore/View/basic_view_with_delete (0.00s)
--- PASS: TestKVStore/View/basic_view_with_put (0.00s)
--- PASS: TestKVStore/Update (0.01s)
--- PASS: TestKVStore/Update/basic_update (0.00s)
--- PASS: TestKVStore/Update/basic_update_with_delete (0.01s)
--- FAIL: TestKVStore/ConcurrentUpdate (1.02s)
--- FAIL: TestKVStore/ConcurrentUpdate/basic_concurrent_update (1.02s)
kv.go:923: error during view transaction: exptected to get value darkness my new friend got world
```

Start with the TestKVStore/ConcurrentUpdate/basic_concurrent_update failure and inspect kv.go:923. Reproduce the concurrent update failure, trace why the expected value differs from the observed value, and verify that the test passes reliably under repeated runs.

Written by the indexing model from the issue text.