cros_build_lib: run: convert a few more .output/.error usage

BUG=b:187789262
TEST=CQ passes

Change-Id: I0db910515a674af43ef36e8611c92ecd2f3205ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3804006
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Cindy Lin <xcl@google.com>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Cindy Lin <xcl@google.com>
diff --git a/scripts/autotest_quickmerge.py b/scripts/autotest_quickmerge.py
index 2901ed8..7b0cc50 100644
--- a/scripts/autotest_quickmerge.py
+++ b/scripts/autotest_quickmerge.py
@@ -404,8 +404,8 @@
                                    args.overwrite)
 
     if args.verbose:
-      logging.info(rsync_output.output)
-    change_report = ItemizeChangesFromRsyncOutput(rsync_output.output,
+      logging.info(rsync_output.stdout)
+    change_report = ItemizeChangesFromRsyncOutput(rsync_output.stdout,
                                                   sysroot_autotest_path)
     num_new_files = num_new_files + len(change_report.new_files)
     num_modified_files = num_modified_files + len(change_report.modified_files)