roachtest: import/mixed-versions failed

[cockroach-teamcity]

roachtest.import/mixed-versions failed with artifacts on master @ dbf711a83969210bcf706d65f53f888856da6ad0:

The test failed on branch=master, cloud=gce:
test artifacts and logs in: /home/agent/work/.go/src/github.com/cockroachdb/cockroach/artifacts/import/mixed-versions/run_1
	import.go:298,test_runner.go:777: prev version not set for version: 21.2
		(1) attached stack trace
		  -- stack trace:
		  | main.PredecessorVersion
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/test_runner.go:1210
		  | main.registerImportMixedVersion.func1
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/import.go:296
		  | main.(*testRunner).runTest.func2
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/test_runner.go:777
		  | runtime.goexit
		  | 	/usr/local/go/src/runtime/asm_amd64.s:1374
		Wraps: (2) prev version not set for version: 21.2
		Error types: (1) *withstack.withStack (2) *errutil.leafError

Reproduce

To reproduce, try:

# From https://go.crdb.dev/p/roachstress, perhaps edited lightly.
caffeinate ./roachstress.sh import/mixed-versions

/cc @cockroachdb/bulk-io

This test on roachdash | Improve this report!

[irfansharif]

Caused due to #64391, +cc @j-low.