zuul: fix gearman-check script
zuul: fix gearman-check script

The script is failing when a project has no check job configured

Change-Id: If3af599387173199899a708c735d9c0dfbcac15f

enovance/software-factory,enovance/software-factory,enovance/software-factory,enovance/software-factory,enovance/software-factory