Merge branch 'tristan/keyboard-interrupt-stack-trace' into 'master'

import asyncio

import multiprocessing

import psutil

# BuildStream toplevel imports

from ..._exceptions import ImplError, BstError, set_last_task_error, SkipJob

from ..._message import Message, MessageType, unconditional_messages

    # Forcefully kill the process, and any children it might have.

    #

    def kill(self):

        # Force kill

        self.message(MessageType.WARN,

                     "{} did not terminate gracefully, killing".format(self.action_name))

        try:

        utils._kill_process_tree(self._process.pid)

        # This can happen if the process died of its own accord before

        # we try to kill it

        except psutil.NoSuchProcess:

            return

    # suspend()

    #

            # Ignore this error, it can happen with

            # some setuid bwrap processes.

            pass

        except psutil.NoSuchProcess:

            # It is certain that this has already been sent

            # SIGTERM, so there is a window where the process

            # could have exited already.

            pass

    # Bloody Murder

    for child in children: