grenade "ping_check_public" failure

eg. http://logs.openstack.org/36/634636/2/check/networking-midonet-grenade-ml2/b901059/logs/grenade.sh.txt.gz

2019-02-04 12:52:29.767 | + /opt/stack/new/grenade/functions:ping_check_public:66 : [[ True = \T\r\u\e ]]
2019-02-04 12:52:29.769 | + /opt/stack/new/grenade/functions:ping_check_public:67 : die 67 '[Fail] Couldn'\''t ping server'
2019-02-04 12:52:29.771 | + /opt/stack/new/devstack/functions-common:die:195 : local exitcode=0
2019-02-04 12:52:29.773 | [Call Trace]
2019-02-04 12:52:29.773 | /opt/stack/new/grenade/projects/60_nova/resources.sh:223:create
2019-02-04 12:52:29.773 | /opt/stack/new/grenade/projects/60_nova/resources.sh:143:ping_check_public
2019-02-04 12:52:29.773 | /opt/stack/new/grenade/functions:67:die
2019-02-04 12:52:29.777 | [ERROR] /opt/stack/new/grenade/functions:67 [Fail] Couldn't ping server
2019-02-04 12:52:30.787 | 1 die /opt/stack/new/devstack/functions-common
2019-02-04 12:52:30.787 | 67 ping_check_public /opt/stack/new/grenade/functions
2019-02-04 12:52:30.787 | 143 create /opt/stack/new/grenade/projects/60_nova/resources.sh
2019-02-04 12:52:30.787 | 223 main /opt/stack/new/grenade/projects/60_nova/resources.sh
2019-02-04 12:52:30.787 | Exit code: 1
2019-02-04 12:52:30.825 | World dumping... see /opt/stack/old/screen-logs/worlddump-2019-02-04-125230.txt for details
2019-02-04 12:52:48.823 | + inc/plugin:resources:123 : die 123 'Failed to run /opt/stack/new/grenade/projects/60_nova/resources.sh create '
2019-02-04 12:52:48.830 | + /opt/stack/new/devstack/functions-common:die:195 : local exitcode=1
2019-02-04 12:52:48.834 | [Call Trace]
2019-02-04 12:52:48.834 | ./grenade.sh:302:resources
2019-02-04 12:52:48.834 | /opt/stack/new/grenade/inc/plugin:123:die
2019-02-04 12:52:48.842 | [ERROR] /opt/stack/new/grenade/inc/plugin:123 Failed to run /opt/stack/new/grenade/projects/60_nova/resources.sh create
2019-02-04 12:52:49.849 | 1 die /opt/stack/new/devstack/functions-common
2019-02-04 12:52:49.849 | 123 resources /opt/stack/new/grenade/inc/plugin
2019-02-04 12:52:49.849 | 302 main ./grenade.sh
2019-02-04 12:52:49.849 | Exit code: 1
2019-02-04 12:52:49.902 | World dumping... see /opt/stack/logs/worlddump-2019-02-04-125249.txt for details