bfd:fix handling session creation batch
bfd:fix handling session creation batch

when multiple session creating script is ran (via exec) only the first
one actually starts

Change-Id: I0fc36f65795c8921cf180e0b555c446e5a80be45
Signed-off-by: Eyal Bari <fc8b6df29e0d3cf2af21713ee0e85afadbf47bf8@cisco.com>

vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp