Honor causeOfStoppage even when process exits with code 0

src/main/java/org/jenkinsci/plugins/workflow/steps/durable_task/DurableTaskStep.java

@@ -678,20 +678,19 @@ private interface OutputSupplier {
             byte[] produce() throws IOException, InterruptedException;
         }
         private void handleExit(int exitCode, OutputSupplier output) throws IOException, InterruptedException {
-            Throwable originalCause = causeOfStoppage;
-            if ((returnStatus && originalCause == null) || exitCode == 0) {
-                getContext().onSuccess(returnStatus ? exitCode : returnStdout ? new String(output.produce(), StandardCharsets.UTF_8) : null);
-            } else {
+            if (causeOfStoppage != null) {
+                getContext().onFailure(causeOfStoppage);
+            } else if (returnStatus) {
+                getContext().onSuccess(exitCode);
+            } else if (exitCode != 0) {
                 if (returnStdout) {
                     _listener().getLogger().write(output.produce()); // diagnostic
                 }
-                if (originalCause != null) {
-                    // JENKINS-28822: Use the previous cause instead of throwing a new AbortException
-                    _listener().getLogger().println("script returned exit code " + exitCode);
-                    getContext().onFailure(originalCause);
-                } else {
-                    getContext().onFailure(new AbortException("script returned exit code " + exitCode));
-                }
+                getContext().onFailure(new AbortException("script returned exit code " + exitCode));
+            } else if (returnStdout) {
+                getContext().onSuccess(new String(output.produce(), StandardCharsets.UTF_8));
+            } else {
+                getContext().onSuccess(null);
             }
             listener().getLogger().close();
         }

src/test/java/org/jenkinsci/plugins/workflow/steps/durable_task/ShellStepTest.java

@@ -778,7 +778,7 @@ private static final class HelloNote extends ConsoleNote<Run<?, ?>> {
         j.waitForCompletion(b);
         // Would have succeeded before https://github.com/jenkinsci/workflow-durable-task-step-plugin/pull/75.
         j.assertBuildStatus(Result.ABORTED, b);
-        j.waitForMessage("Timeout has been exceeded", b); // TODO assertLogContains fails unless a sleep is introduced; possible race condition in waitForCompletion
+        j.assertLogContains("Timeout has been exceeded", b);
     }
 
     @Issue("JENKINS-62014")