Fix interprocess locks for run_tests.sh
Fix interprocess locks for run_tests.sh

This was fixed for nova using this method and we are porting it here as we are
running into a similar bug as #1264058

Closes-Bug: #1269938
Change-Id: I06a2684629fd7b4d30e2d7716dc00a2ed0479f2f

openstack/networking-bigswitch,wolverineav/networking-bigswitch,stackforge/networking-bigswitch,wolverineav/networking-bigswitch,openstack/networking-bigswitch,stackforge/networking-bigswitch