cros_build_lib: RunCommandError: avoid use of result

The result property already has all of its properties split out into
RunCommandError directly, so there's no need for this thing.  Plus,
the subprocess APIs don't have anything similar.  Avoid use of it in
most places.

BUG=b:187789262
TEST=CQ passes

Change-Id: I257f8868e274bbfe5549df0ca27078e288fa2601
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3838862
Commit-Queue: Lizzy Presland <zland@google.com>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Lizzy Presland <zland@google.com>
diff --git a/scripts/cros_merge_to_branch.py b/scripts/cros_merge_to_branch.py
index 06e53c4..885ef62 100644
--- a/scripts/cros_merge_to_branch.py
+++ b/scripts/cros_merge_to_branch.py
@@ -131,8 +131,8 @@
           patch.project_url, 'refs/%s/%s' % (upload_type, branch),
           carbon_copy=False, dryrun=dryrun, reviewers=reviewers)
     except cros_build_lib.RunCommandError as e:
-      if (e.result.returncode == 128 and
-          re.search(r'fatal: user ".*?" not found', e.result.stderr)):
+      if (e.returncode == 128 and
+          re.search(r'fatal: user ".*?" not found', e.stderr)):
         logging.warning('Some reviewers were not found (%s); '
                         'dropping them & retrying upload', ' '.join(reviewers))
         continue