am a80cc6eb: Merge change 3184 into donut

Merge commit 'a80cc6ebe7426792927cddbf191bb7435a06fc5e'

* commit 'a80cc6ebe7426792927cddbf191bb7435a06fc5e':
  The '-D' option for the 'am' command appears to be optional, so reflect that in the usage.