2.0 branch bug: Tests that cause [HALT] events in big runs leave Test2 in a bad state, unable to exit without ctrl+c

[troglodyne]

This one may be a doozy to replicate/debug. That said, this is what I've been using to run yath 2.0 to try to smoke cPanel's perl tests:

PERL5LIB='/usr/local/cpanel/t/lib' /usr/local/cpanel/3rdparty/perl/542/bin/yath test -B --qvf --no-progress --no-unsafe-inc --no-blib --no-lib --no-tlib -P FindBin -P Test::More --retry=1 --retry-isolated --term-size 2000 --extension t --switch=-w --durations build-tools/yath-durations.json --renderer TAPHarness -j`perl -E 'say int( 1.0 * int qx{nproc} )'`  --renderer DB --publish-mode complete --cover-files --project 'smoke-perl:8f7ee6d107a:cloudlinux9:10.2.64.170' --db-config Test2::Harness::UI::Config::Cpanel  --exclude-file    t/00_cplint.t --exclude-pattern t/benchmark/ --exclude-pattern t/broken/ --exclude-pattern t/final/ --exclude-pattern t/integration/ --exclude-pattern t/js/ --exclude-pattern t/qa/ --exclude-pattern t/support/ --exclude-pattern t/unreliable/ --exclude-pattern t/zz t

We are reporting in to a remote DB, but that doesn't appear to be causing issues in particular. Instead if one of the tests winds up causing a HALT, then the whole run seems borked until we ctrl+c it:

[  HALT  ]  job 28    IPC Fatal Error: hub '1166772~0~1758818045~2' is not available, failed to send event!
(TO RETRY)  job 29    t/Cpanel-Wrap.t
< REASON >  job 29    Test script returned error (Signal: 15)
< REASON >  job 29    No plan was declared
(TO RETRY)  job 40    t/etc-rpm.versions_perlmajor_upgrade.t
< REASON >  job 40    Test script returned error (Signal: 15)
< REASON >  job 40    No plan was declared, and no assertions were made.
(TO RETRY)  job 20    t/Cpanel-MariaDB-Install.t
< REASON >  job 20    Test script returned error (Signal: 15)
< REASON >  job 20    Planned for 62 assertions, but saw 33
(TO RETRY)  job 53    t/large/detect-unused-packages.t
< REASON >  job 53    Test script returned error (Signal: 15)
< REASON >  job 53    No plan was declared
(TO RETRY)  job 28    t/Cpanel-Server-Handlers-Httpd.t
< REASON >  job 28    Test script returned error (Signal: 15)
< REASON >  job 28    Errors were encountered (Count: 1)
< REASON >  job 28    Planned for 106 assertions, but saw 6
(  DIAG  )  job 3     Looks like you planned 11255 tests but ran 5.
(TO RETRY)  job 3     t/01_devel_smoke_p.t
< REASON >  job 3     Test script returned error (Err: 255)
< REASON >  job 3     Planned for 11255 assertions, but saw 5
(TO RETRY)  job 42    t/large/06_Template_security.t
< REASON >  job 42    Test script returned error (Signal: 15)
< REASON >  job 42    Planned for 1 assertions, but saw 0
( STDERR )  RUNNER    Testing looks complete, but a filehandle is still open (Did a plugin or renderer fork without an exec?), will timeout in 10 seconds...
( STDERR )  RUNNER      9...
( STDERR )  RUNNER      8...
( STDERR )  RUNNER      7...
( STDERR )  RUNNER      6...
( STDERR )  RUNNER      5...
( STDERR )  RUNNER      4...
( STDERR )  RUNNER      3...
( STDERR )  RUNNER      2...
(TO RETRY)  job 48    t/large/Cpanel-PingTest.t
< REASON >  job 48    Test script returned error (Signal: 15)
< REASON >  job 48    Planned for 15 assertions, but saw 6
( STDERR )  RUNNER    Testing looks complete, but a filehandle is still open (Did a plugin or renderer fork without an exec?), will timeout in 10 seconds...
( STDERR )  RUNNER      9...
( STDERR )  RUNNER      8...
( STDERR )  RUNNER      7...
( STDERR )  RUNNER      6...
( STDERR )  RUNNER      5...
( STDERR )  RUNNER      4...
( STDERR )  RUNNER      3...
( STDERR )  RUNNER      2...
( STDERR )  RUNNER      1...
( STDERR )  RUNNER      0...

( STDERR )  RUNNER      (in cleanup) Disconnected pipe at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/Test2/Harness/Instance.pm line 382.

If I wind up finding a fix myself, I'll probably submit it, but any assistance would of course be appreciated. That said I have actually had to make a few patches along the way here when running things that could complicate this:
troglodyne@b52b60e#diff-7db323a2448800b006f5d6f74c00fc2031878d36a9218ba2d73142206202c5a1

As far as I can tell, the run explodes before running anything when orig_tmp is not set, which appears to always be the case:

The 'orig_tmp' option does not exist at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/Getopt/Yath/Settings/Group.pm line 74.                                                                                            Getopt::Yath::Settings::Group::AUTOLOAD(Getopt::Yath::Settings::Group=HASH(0x2949230)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath/IPC.pm line 50
        App::Yath::IPC::dir(App::Yath::IPC=HASH(0x21c47c8)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath/IPC.pm line 78
        App::Yath::IPC::_find_ipcs(App::Yath::IPC=HASH(0x21c47c8)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath/IPC.pm line 71
        App::Yath::IPC::ipcs(App::Yath::IPC=HASH(0x21c47c8)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath/IPC.pm line 310                                                                           App::Yath::IPC::find(App::Yath::IPC=HASH(0x21c47c8)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath.pm line 431                                                                               App::Yath::process_args(App::Yath=HASH(0x21c4318)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath.pm line 505                                                                                 App::Yath::run(App::Yath=HASH(0x21c4318)) called at /usr/local/cpanel/3rdparty/perl/542/cpanel-lib/App/Yath/Script.pm line 62
        App::Yath::Script::run("/usr/local/cpanel/3rdparty/perl/542/bin/yath", ARRAY(0x16155b8)) called at /usr/local/cpanel/3rdparty/perl/542/bin/yath line 24

Certainly there's nothing in POD or the help output that suggests this is an actual option.
I patched this to be at least something that should work on the majority of systems (hardcode /tmp), but this may not be an assumption the rest of the application respects. Not really sure. That certainly might explain some oddities regarding a failure to find things that it was expecting.