Handle no results by grep not to exit

Signed-off-by: Jose Luis Rivero <[email protected]>

jenkins-scripts/dsl/dsl_checks.bash

@@ -53,7 +53,8 @@ fi
 # Check that whiteListedTargetBranches are non empty in all generated gazebo_libs
 # see https://github.com/gazebo-tooling/release-tools/pull/1144
 # For other jobs the use case is valid since pr can be enabled on all branches
-empty_branches_on_github_triggered=$(grep '<whiteListTargetBranches></whiteListTargetBranches>' -- {gz_,sdformat}*{-abichecker-,-pr_any-}*.xml)
+empty_branches_on_github_triggered=$(grep '<whiteListTargetBranches></whiteListTargetBranches>' \
+                                      -- {gz_,sdformat}*{-abichecker-,-pr_any-}*.xml || true)
 if [[ -n ${empty_branches_on_github_triggered} ]]; then
   echo "Unexpected whiteListTargetBranches without values. It will trigger all branches:"
   echo "${empty_branches_on_github_triggered}"