cli/scripts: more cros_build_lib.run API migrations

BUG=b:187789262
TEST=CQ passes

Change-Id: Idcc78ccfe14fdbae89ae7573d6e78036bdacf8ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3738519
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Ram Chandrasekar <rchandrasekar@google.com>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Ram Chandrasekar <rchandrasekar@google.com>
diff --git a/scripts/loman.py b/scripts/loman.py
index 5f34ee9..81961e3 100644
--- a/scripts/loman.py
+++ b/scripts/loman.py
@@ -78,7 +78,7 @@
   git_config = options.git_config
 
   cmd = ['config', '-f', git_config, '--get', 'manifest.groups']
-  enabled_groups = git.RunGit('.', cmd, check=False).output.rstrip().split(',')
+  enabled_groups = git.RunGit('.', cmd, check=False).stdout.rstrip().split(',')
 
   # Note that ordering actually matters, thus why the following code
   # is written this way.