github.com/cockroachdb/pebble/internal/metamorphic: TestMetaCockroachKVs failed

github.com/cockroachdb/pebble/internal/metamorphic.TestMetaCockroachKVs [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_NightlyPebbleMetamorphicRace/21511208?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_NightlyPebbleMetamorphicRace/21511208?buildTab=artifacts#meta) on master @ [f8638b9298c5](https://github.com/cockroachdb/pebble/commits/f8638b9298c5):

```
[TestOptions]
key_format=cockroachkvs
strictfs=true
basaltfs=true
replace_single_delete=true
threads=5
enable_value_blocks=true
async_apply_to_db=true
seed_efos=15857245915282859860
mem_buf_max_file_bytes=1746419
mem_buf_budget_bytes=3227574
disable_downloads=true

===== OPS =====
/artifacts/meta/260911-042714.5222242456019/ops
===== HISTORY =====
/artifacts/meta/260911-042714.5222242456019/random-025/history
...[196445 lines skipped]...
// 04:37:35.364 INFO: github.com/cockroachdb/pebble.(*Iterator).Clone
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/iterator.go:3128
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.(*newIterUsingCloneOp).run
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/ops.go:1723
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.(*Test).runOp
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/test.go:563
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.Execute.func1
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/meta.go:724
// 04:37:35.364 INFO: golang.org/x/sync/errgroup.(*Group).Go.func1
// 04:37:35.364 INFO: external/org_golang_x_sync/errgroup/errgroup.go:93
// 04:37:35.364 INFO: runtime.goexit
// 04:37:35.364 INFO: src/runtime/asm_amd64.s:1771
// 04:37:35.364 INFO:
// 04:37:35.364 INFO: started 10m0.084936567s ago:
// 04:37:35.364 INFO: github.com/cockroachdb/pebble.(*DB).newIter
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/db.go:1348
// 04:37:35.364 INFO: github.com/cockroachdb/pebble.(*DB).NewIterWithContext
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/db.go:1964
// 04:37:35.364 INFO: github.com/cockroachdb/pebble.(*DB).NewIter
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/db.go:1958
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.(*newIterOp).run
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/ops.go:1631
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.(*Test).runOp
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/test.go:563
// 04:37:35.364 INFO: github.com/cockroachdb/pebble/metamorphic.Execute.func1
// 04:37:35.364 INFO: external/com_github_cockroachdb_pebble/metamorphic/meta.go:724
// 04:37:35.364 INFO: golang.org/x/sync/errgroup.(*Group).Go.func1
// 04:37:35.364 INFO: external/org_golang_x_sync/errgroup/errgroup.go:93
// 04:37:35.364 INFO:

To reduce: go test ./internal/metamorphic -tags invariants -run 'TestMetaCockroachKVs$' --run-dir /artifacts/meta/260911-042714.5222242456019/random-025 --try-to-reduce -v
--- FAIL: TestMetaCockroachKVs/execution/random-025 (606.30s)
```
Help

To reproduce, try:

```bash
go test -tags 'invariants' -exec 'stress -p 1' -timeout 0 -test.v -run 'TestMetaCockroachKVs$' ./internal/metamorphic -seed 1789100834522304852 -ops "uniform:5000-10000"
```

[Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: PEBBLE-1479

Start in internal/metamorphic with TestMetaCockroachKVs and reproduce using the provided stress command and seed. Inspect the linked TeamCity artifacts and try the supplied --try-to-reduce command to isolate the failure. Done means identifying and fixing the cause, then confirming the reduced case and reproduction pass.

Written by the indexing model from the issue text.