Updated openstack/openstack
Project: openstack/neutron  797fa55fef2e28cce9dd8f06009217e57bb31e91

Make pid file locking non-blocking

fcntl.flock will block indefinitely if another process holds an exclusive
lock. A non-blocking flock operation will raise an error when a lock already
exists so we can fail immediately.

Closes-bug: 1315507
Change-Id: Icf97b1f8643157719b3d28ac2c0c1576a5069697