Fix test failure: dtest-upgrade.upgrade_tests.upgrade_through_versions_test.TestProtoV3Upgrade_AllVersions_RandomPartitioner_EndsAt_3_11_X_HEAD.test_rolling_upgrade

self = <upgrade_tests.upgrade_through_versions_test.TestProtoV3Upgrade_AllVersions_RandomPartitioner_EndsAt_3_11_X_HEAD object at 0x7fb75c2087c0>

    @pytest.mark.timeout(3000)
    def test_rolling_upgrade(self):
        """
            Test rolling upgrade of the cluster, so we have mixed versions part way through.
            """
>       self.upgrade_scenario(rolling=True)

upgrade_tests/upgrade_through_versions_test.py:320: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
upgrade_tests/upgrade_through_versions_test.py:398: in upgrade_scenario
    self._check_on_subprocs(self.fixture_dtest_setup.subprocs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <upgrade_tests.upgrade_through_versions_test.TestProtoV3Upgrade_AllVersions_RandomPartitioner_EndsAt_3_11_X_HEAD object at 0x7fb75c2087c0>
subprocs = [<Process name='Process-1' pid=19049 parent=301 stopped exitcode=-SIGKILL daemon>, <Process name='Process-2' pid=19070 parent=301 stopped exitcode=1 daemon>]

    def _check_on_subprocs(self, subprocs):
        """
            Check on given subprocesses.
    
            If any are not alive, we'll go ahead and terminate any remaining alive subprocesses since this test is going to fail.
            """
        subproc_statuses = [s.is_alive() for s in subprocs]
        if not all(subproc_statuses):
            message = "A subprocess has terminated early. Subprocess statuses: "
            for s in subprocs:
                message += "{name} (is_alive: {aliveness}), ".format(name=s.name, aliveness=s.is_alive())
            message += "attempting to terminate remaining subprocesses now."
            self._terminate_subprocs()
>           raise RuntimeError(message)
E           RuntimeError: A subprocess has terminated early. Subprocess statuses: Process-1 (is_alive: True), Process-2 (is_alive: False), attempting to terminate remaining subprocesses now.

upgrade_tests/upgrade_through_versions_test.py:456: RuntimeError