Don't fail the build if signing fails

Output an error if signing fails, but don't fail the build. This is
needed to make it possible to run the builds from private test
environments without requiring the signing step to pass.

Signed-off-by: Henri Rosten <[email protected]>

utils.groovy

@@ -162,12 +162,16 @@ def find_img_relpath(String flakeref, String subdir, String abort_on_error="true
 
 def sign_file(String path, String sigfile, String cert="INT-Ghaf-Devenv-Common") {
   println "sign_file: ${path} ### ${cert} ### ${sigfile}"
-  sh(
-    // See the 'sign' command at: https://github.com/tiiuae/ci-yubi
-    script: """
-      mkdir -p \$(dirname '${sigfile}') || true
-      sign --path=${path} --cert=${cert} --sigfile=${sigfile}
+  try {
+    sh(
+      // See the 'sign' command at: https://github.com/tiiuae/ci-yubi
+      script: """
+        mkdir -p \$(dirname '${sigfile}') || true
+        sign --path=${path} --cert=${cert} --sigfile=${sigfile}
     """, returnStdout: true).trim()
+  } catch (Exception e) {
+    println "Warning: signing failed: sigfile will not be generated for: ${path}"
+  }
 }
 
 def ghaf_hw_test(String flakeref, String device_config, String jenkins_url, String testset='_boot_') {