clear db._ENGINE for each plugin init in Metaplugin
clear db._ENGINE for each plugin init in Metaplugin

Fixes bug 1036996

Change-Id: I7f289b4ccda281a66666ec1dbf7fc01156b0512c

apporc/neutron,liqin75/vse-vpnaas-plugin,armando-migliaccio/neutron,chitr/neutron,yamt/neutron,silenci/neutron,noironetworks/neutron,jacknjzhou/neutron,adelina-t/neutron,cernops/neutron,magic0704/neutron,NeCTAR-RC/neutron,yanheven/neutron,CiscoSystems/neutron,kaiweifan/vse-lbaas-plugin-poc,apporc/neutron,mmnelemane/neutron,wolverineav/neutron,vivekanand1101/neutron,takeshineshiro/neutron,mahak/neutron,yamahata/tacker,gopal1cloud/neutron,vivekanand1101/neutron,leeseuljeong/leeseulstack_neutron,neoareslinux/neutron,skyddv/neutron,barnsnake351/neutron,eayunstack/neutron,rdo-management/neutron,Comcast/neutron,CiscoSystems/quantum,liqin75/vse-vpnaas-plugin,wolverineav/neutron,vveerava/Openstack,vijayendrabvs/hap,mattt416/neutron,kaiweifan/vse-lbaas-plugin-poc,infobloxopen/neutron,ntt-sic/neutron,Comcast/neutron,openstack/neutron,blueboxgroup/neutron,watonyweng/neutron,beagles/neutron_hacking,MaximNevrov/neutron,shahbazn/neutron,rossella/neutron,kaiweifan/neutron,vveerava/Openstack,Juniper/contrail-dev-neutron,javaos74/neutron,klmitch/neutron,gkotton/neutron,gkotton/neutron,alexandrucoman/vbox-neutron-agent,blueboxgroup/neutron,sasukeh/neutron,mandeepdhami/neutron,armando-migliaccio/neutron,CiscoSystems/quantum,redhat-openstack/neutron,asgard-lab/neutron,virtualopensystems/neutron,asgard-lab/neutron,alexandrucoman/vbox-neutron-agent,cernops/neutron,rossella/neutron,SamYaple/neutron,cisco-openstack/neutron,ykaneko/neutron,vbannai/neutron,vbannai/neutron,psiwczak/quantum,rickerc/neutron_audit,kaiweifan/neutron,aristanetworks/arista-ovs-quantum,Brocade-OpenSource/OpenStack-DNRM-Neutron,yamahata/neutron,openstack/neutron,jerryz1982/neutron,bigswitch/neutron,mahak/neutron,yuewko/neutron,redhat-openstack/neutron,bigswitch/neutron,vijayendrabvs/ssl-neutron,sajuptpm/neutron-ipam,Juniper/contrail-dev-neutron,aristanetworks/arista-ovs-quantum,ykaneko/quantum,glove747/liberty-neutron,cloudbase/neutron-virtualbox,oeeagle/quantum,glove747/liberty-neutron,antonioUnina/neutron,cisco-openstack/neutron,magic0704/neutron,swdream/neutron,NeCTAR-RC/neutron,kaiweifan/vse-lbaas-plugin-poc,projectcalico/calico-neutron,SmartInfrastructures/neutron,virtualopensystems/neutron,rickerc/neutron_audit,CiscoSystems/vespa,projectcalico/calico-neutron,armando-migliaccio/neutron,gkotton/neutron,igor-toga/local-snat,blueboxgroup/neutron,gopal1cloud/neutron,infobloxopen/neutron,leeseuljeong/leeseulstack_neutron,igor-toga/local-snat,cloudbase/neutron-virtualbox,huntxu/neutron,FreescaleSemiconductor/quantum,CiscoSystems/neutron,aristanetworks/arista-ovs-quantum,jacknjzhou/neutron,JioCloud/neutron,mahak/neutron,eonpatapon/neutron,zhhf/charging,waltBB/neutron_read,paninetworks/neutron,cloudbase/neutron,sajuptpm/neutron-ipam,pnavarro/neutron,openstack/neutron,yanheven/neutron,psiwczak/quantum,waltBB/neutron_read,JianyuWang/neutron,jumpojoy/neutron,psiwczak/quantum,zhhf/charging,dims/neutron,leeseulstack/openstack,JianyuWang/neutron,CiscoSystems/neutron,yamt/neutron,Comcast/neutron,jumpojoy/neutron,skyddv/neutron,leeseulstack/openstack,ykaneko/quantum,ykaneko/quantum,Metaswitch/calico-neutron,tpaszkowski/quantum,vbannai/neutron,kaiweifan/vse-lbaas-plugin-poc,rdo-management/neutron,aristanetworks/arista-ovs-quantum,tpaszkowski/quantum,tpaszkowski/quantum,sasukeh/neutron,FreescaleSemiconductor/quantum,netscaler/neutron,suneeth51/neutron,vijayendrabvs/ssl-neutron,ykaneko/quantum,ykaneko/neutron,FreescaleSemiconductor/quantum,watonyweng/neutron,netscaler/neutron,miyakz1192/neutron,mattt416/neutron,citrix-openstack-build/neutron,wenhuizhang/neutron,wenhuizhang/neutron,sebrandon1/neutron,psiwczak/quantum,bgxavier/neutron,zhhf/charging,sajuptpm/neutron-ipam,jerryz1982/neutron,liqin75/vse-vpnaas-plugin,ykaneko/neutron,barnsnake351/neutron,javaos74/neutron,CiscoSystems/vespa,silenci/neutron,vijayendrabvs/hap,aristanetworks/neutron,Juniper/neutron,sebrandon1/neutron,MaximNevrov/neutron,swdream/neutron,FreescaleSemiconductor/quantum,adelina-t/neutron,CiscoSystems/quantum,dims/neutron,citrix-openstack-build/neutron,klmitch/neutron,shahbazn/neutron,vijayendrabvs/hap,yamt/neutron,bgxavier/neutron,yamahata/tacker,mmnelemane/neutron,SmartInfrastructures/neutron,beagles/neutron_hacking,yuewko/neutron,huntxu/neutron,eayunstack/neutron,noironetworks/neutron,suneeth51/neutron,mandeepdhami/neutron,leeseuljeong/leeseulstack_neutron,Stavitsky/neutron,yamahata/neutron,takeshineshiro/neutron,dhanunjaya/neutron,paninetworks/neutron,yamahata/tacker,vveerava/Openstack,ntt-sic/neutron,beagles/neutron_hacking,neoareslinux/neutron,eonpatapon/neutron,tpaszkowski/quantum,rickerc/neutron_audit,antonioUnina/neutron,CiscoSystems/vespa,netscaler/neutron,Juniper/neutron,kaiweifan/neutron,SamYaple/neutron,armando-migliaccio/neutron,virtualopensystems/neutron,pnavarro/neutron,Brocade-OpenSource/OpenStack-DNRM-Neutron,aristanetworks/neutron,chitr/neutron,oeeagle/quantum,Brocade-OpenSource/OpenStack-DNRM-Neutron,Metaswitch/calico-neutron,leeseulstack/openstack,Stavitsky/neutron,rossella/neutron,cloudbase/neutron,yamahata/neutron,liqin75/vse-vpnaas-plugin,citrix-openstack-build/neutron,yamt/neutron,JioCloud/neutron,Juniper/contrail-dev-neutron,ntt-sic/neutron,rossella/neutron,dhanunjaya/neutron,Juniper/neutron,miyakz1192/neutron,vijayendrabvs/ssl-neutron