builder: upload the compose json

Upload the final compose status as JSON, so it can be inspected,
which could be especially handy if multiple image requests were
made and only one of them failed, to quickly pin down the one
that failed, without having to go through all the logs.

plugins/builder/osbuild.py

@@ -405,6 +405,7 @@ class OSBuildImage(BaseTaskHandler):
         self.logger.debug("Compose finished: %s", str(status.as_dict()))
         self.logger.info("Compose result: %s", status.status)
 
+        self.upload_json(status.as_dict(), "compose-status")
         self.attach_logs(cid, ireqs)
 
         if not status.is_success: