__PACKAGE__->builder->reset; いれると直る...

test.t

package MyTest;
use utf8;
use strict;
use warnings;
use parent qw(Test::Class);

use Test::More;

sub t1 : Tests {
    subtest 'is it ok if I die?' => sub {
        die "I'l die";
    };
}

sub t2 : Tests {
    __PACKAGE__->builder->reset;
    subtest 'okokokok!!!' => sub {
        ok 1;
    };
}

__PACKAGE__->runtests();

__END__

prove test.t
test.t .. #
# MyTest->t1
    # Child (is it ok if I die?) exited without calling finalize()

not ok 1 - is it ok if I die?
not ok 2 - t1 died (I'l die at test.t line 11.)

#   Failed test 'is it ok if I die?'
#   at /Users/yuuki/.plenv/versions/5.14.4/lib/perl5/site_perl/5.14.4/Test/Class.pm line 289.
#   (in MyTest->t1)

#   Failed test 't1 died (I'l die at test.t line 11.)'
#   at test.t line 22.
#   (in MyTest->t1)
#
# MyTest->t2
    ok 1 - t2
    1..1
ok 1 - okokokok!!!
# Tests were run but no plan was declared and done_testing() was not seen.
Failed 2/3 subtests

Test Summary Report
-------------------
test.t (Wstat: 0 Tests: 3 Failed: 2)
  Failed tests:  1-2
  Parse errors: Tests out of sequence.  Found (1) but expected (3)
                No plan found in TAP output
Files=1, Tests=3,  0 wallclock secs ( 0.03 usr  0.01 sys +  0.03 cusr  0.00 csys =  0.07 CPU)
Result: FAIL