exception in parallel task - fabfile boilerplate

fabfile.py

from fabric.api import env, execute, lcd, task, settings
from fabric.decorators import runs_once, parallel

env.roledefs = {
    'foo': ['bar1', 'bar2', 'bar3']
}


class FabricAbortException(Exception):
    pass


@task
@parallel
def parallel_task():
    if env.host_string != 'bar1':
        raise Exception("error in %s" % env.host_string)

    print("success for %s" % env.host_string)


@runs_once
@task
def main_task():
    thrown_error = None
    errors_fired = 0
    with settings(abort_exception=FabricAbortException):
        try:
            with lcd("/tmp"):
                execute(parallel_task)
        except Exception as err:
            thrown_error = err
            errors_fired += 1

    if thrown_error is not None:
        print("errors fired: %s" % errors_fired)
        raise thrown_error

    print("all done")