test_runner.t fails on Perl 5.38.0 GNU/Linux

[FAIL Process-SubProcess-2.1.2 5.38.0 GNU/Linux](http://www.cpantesters.org/cpan/report/fd51bef8-33e4-11ee-a67c-5392925487fb)
```plain
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PROGRAM OUTPUT
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Output from '/usr/bin/make test':

PERL_DL_NONLAZY=1 "/home/david/cpantesting/perl-5.38.0-SILENT_NO_TAINT/bin/perl" "-MExtUtils::Command::MM" "-MTest::Harness" "-e" "undef *Test::Harness::Switches; test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/test_group.t ........ ok
t/test_performance.t .. ok
Can't modify undef operator in scalar assignment at t/test_runner.t line 154, near "undef;"
Execution of t/test_runner.t aborted due to compilation errors.
t/test_runner.t .......
Dubious, test returned 255 (wstat 65280, 0xff00)
No subtests run
t/test_subprocess.t ... ok

Test Summary Report
-------------------
t/test_runner.t (Wstat: 65280 (exited 255) Tests: 0 Failed: 0)
Non-zero exit status: 255
Parse errors: No plan found in TAP output
Files=4, Tests=12, 62 wallclock secs ( 0.12 usr 0.02 sys + 2.80 cusr 0.55 csys = 3.49 CPU)
Result: FAIL
Failed 1/4 test programs. 0/12 subtests failed.
make: *** [Makefile:883: test_dynamic] Error 255
```