Comment 2 for bug 1709931

Reviewed: https://review.openstack.org/492107
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=82d468ba7fd6dce91fec015d39126e71c1434fb1
Submitter: Zuul
Branch: master

commit 82d468ba7fd6dce91fec015d39126e71c1434fb1
Author: Lucian Petrut <email address hidden>
Date: Wed Aug 9 13:50:09 2017 +0300

    Windows: fix exec calls

    At some point, we've switched to an alternative process launcher
    that uses named pipes to communicate with the child processes. This
    implementation has some issues, truncating the process output in some
    situations.

    This change switches back to subprocess.Popen, which is a much easier
    and convenient way to perform exec calls. We're also ensuring that the
    os module is not patched (which would cause subprocess.Popen to fail
    on Windows due to an eventlet limitation, the reason why the above
    mentioned implementation was first introduced).

    We're also ensuring that such calls do not block other greenthreads
    by leveraging eventlet.tpool.

    Side note: I had to store subprocess.Popen in a variable in order
    to avoid having OpenStack bandit complaining, even though we're
    explicitly passing "shell=False":
    http://paste.openstack.org/raw/658319/

    Closes-Bug: #1709931

    Change-Id: Ib58e12030e69ea10862452c2f141a7a5f2527621