Fix conditional check for multi-site deploys
Fix conditional check for multi-site deploys

Fixes "error while evaluating conditional" error when deploying multiple sites one by one.  Ansible needs to check if the variable "is defined" since its not a straight boolean true/false check.
jeffstieler/bedrock-ansible,pressbooks/trellis,partounian/trellis,ThemeSurgeon/trellis,ChilliCreative/trellis,kalenjohnson/trellis,dailysecret/trellis,cimocimocimo/cimo-wordpress-server,Twansparant/trellis-db-sync,jeffstieler/bedrock-ansible,newtonne/trellis,kalenjohnson/trellis,rpkoller/trellis,fullyint/trellis,afonsoduarte/ansible-stacey,cimocimocimo/cimo-wordpress-server,ChilliCreative/trellis,pressbooks/trellis,mAAdhaTTah/bedrock-ansible,mlaa/trellis,jvandijk/epwp-trellis,jwkicklighter/trellis,roots/trellis,alan-c/trellis,erikbelusic/trellis,jvandijk/epwp-trellis,kalenjohnson/trellis,fusionpig/trellis,NicBeltramelli/trellis,BrandonShutter/trellis,newtonne/trellis,Twansparant/trellis-db-sync,louim/bedrock-ansible,bbttxu/trellis,patrickheeney/trellis,partounian/trellis,fullyint/trellis,mlaa/trellis,partounian/trellis,BrandonShutter/trellis,drewrawitz/wp-ansible,dailysecret/trellis,partounian/trellis,newtonne/trellis,merchantguru/trellis,buluma/trellis,creditera/trellis,alan-c/trellis,SecureCloud-biz/trellis,afonsoduarte/ansible-stacey,drawcard/trellis,jeffstieler/bedrock-ansible,proteusthemes/pt-ops,mAAdhaTTah/bedrock-ansible,kulturavashchi/trellis,mAAdhaTTah/bedrock-ansible,Twansparant/trellis-db-sync,kalenjohnson/trellis,buluma/trellis,fullyint/trellis,jwall/trellis,NicBeltramelli/trellis,jvandijk/trellis,NicBeltramelli/trellis,ckovey/trellis,proteusthemes/pt-ops,dboune/trellis,roots/bedrock-ansible,roots/bedrock-ansible,evanfuture/trellis,fullyint/trellis,Twansparant/trellis-db-sync,ckovey/trellis,all9lives/trellis,rogeruiz/trellis,roots/trellis,buluma/trellis,cimocimocimo/cimo-wordpress-server,all9lives/trellis,mAAdhaTTah/bedrock-ansible,cimocimocimo/cimo-wordpress-server,proteusthemes/pt-ops,skynet/trellis,NicBeltramelli/trellis,austinpray/bedrock-ansible,dboune/trellis,buluma/trellis,dmin7b5/trellis