Loosen up the thread death failure expectations

Sometimes the test fails with "SystemExit: 123", which is OK with me.
Not *ideal* that there is not homogeneous behavior across all executions
and platforms, but both of these failure messages are reasonable.

Author: ctrueden

src/test/java/org/apposed/appose/ServiceTest.java

@@ -169,9 +169,14 @@ public void testPythonSysExit() throws InterruptedException, IOException {
 			// that Appose's python_worker handles this situation well.
 			Task task = service.task("import sys\nsys.exit(123)").waitFor();
 
-			// Is the tag flagged as failed due to thread death?
+			// Is the tag flagged as failed?
 			assertSame(TaskStatus.FAILED, task.status);
-			assertEquals("thread death", task.error);
+
+			// The failure should be either "thread death" or a "SystemExit" message.
+			assertTrue(
+				task.error.equals("thread death") ||
+				task.error.contains("SystemExit: 123")
+			);
 		}
 	}