basalt-26.3.2-rc-20260916: kv/kvserver: TestStoreRangeMergeSplitRace_MergeWins failed

kv/kvserver.TestStoreRangeMergeSplitRace_MergeWins [failed](https://mesolite.cluster.engflow.com/invocations/default/6d298377-987e-4619-be53-5ce590e72dc3?testReportRun=1&testReportShard=13&testReportAttempt=1#targets-Ly9wa2cva3Yva3ZzZXJ2ZXI6a3ZzZXJ2ZXJfdGVzdA==) on basalt-26.3.2-rc-20260916 @ [20b5b7762461dc7d59206ab797cd12d09c877eaa](https://github.com/cockroachdb/cockroach/commits/20b5b7762461dc7d59206ab797cd12d09c877eaa):

```
=== RUN TestStoreRangeMergeSplitRace_MergeWins
test_log_scope.go:172: test logs captured to: outputs.zip/logTestStoreRangeMergeSplitRace_MergeWins3118687690
test_log_scope.go:82: use -show-logs to present logs inline
test_server_shim.go:146: using test tenant configuration from testserver factory defaults
client_merge_test.go:1655: merge failed: checking RHS manifest before merge: descriptor generation mismatch: expected 2, found 3
panic.go:694: -- test log scope end --
test logs left over in: outputs.zip/logTestStoreRangeMergeSplitRace_MergeWins3118687690
--- FAIL: TestStoreRangeMergeSplitRace_MergeWins (5.12s)
```

Parameters:
- attempt=1
- race=true
- run=1
- shard=13
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

Same failure on other branches

- #175040 basalt-26.3: kv/kvserver: TestStoreRangeMergeSplitRace_MergeWins failed [C-test-failure O-robot P-3 T-kv X-duplicate branch-basalt-26.3]
- #174984 basalt-26.3.2-rc-20260908: kv/kvserver: TestStoreRangeMergeSplitRace_MergeWins failed [C-test-failure O-robot P-3 T-kv X-duplicate branch-basalt-26.3.2-rc-20260908]
- #174777 kv/kvserver: TestStoreRangeMergeSplitRace_MergeWins failed [A-testing C-bug C-test-failure O-robot P-3 T-kv branch-master]

/cc @cockroachlabs/kv-triage

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*TestStoreRangeMergeSplitRace_MergeWins.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Start with kv/kvserver.TestStoreRangeMergeSplitRace_MergeWins and the failure at client_merge_test.go:1655; review the referenced test logs and linked invocation. Reproduce the race-enabled test and investigate the descriptor generation mismatch during the merge. Done means the test no longer reports the merge failure reliably.

Written by the indexing model from the issue text.