Minor cleanup.
Split 'common/' into commit '2ec74cd6a633a48f44e84124911d7d87e6c0a6bd'

git-subtree-dir: common
git-subtree-mainline: b4e3ad3207cbe0620f553d9f07260d8f3734b535
git-subtree-split: 2ec74cd6a633a48f44e84124911d7d87e6c0a6bd