fix output download failure detection

jess/backends/arc.py

@@ -96,7 +96,7 @@ class ARC(jess.backends.PluginBase):
 
         if not stat:
             raise jess.JobOutputError("Failed to get job output", ret_code=ret_code, details=stdout, cmd=' '.join(cmd))
-        if 'WARN' in stdout or 'ERROR'in stdout:
+        if 'ERROR' in stdout:
             raise jess.JobOutputError("Failed to get job output", ret_code=ret_code, details=stdout, cmd=' '.join(cmd))
 
         match = re.search('Results stored at: (.*)', stdout)