Add 'modules/zuul/' from commit 'b7bf5b2807128e3bb5e080e952e9de0e9e70b80a'

git-subtree-dir: modules/zuul
git-subtree-mainline: 407682a2a274e15a7ea3c01b560401df8396a0ce
git-subtree-split: b7bf5b2807128e3bb5e080e952e9de0e9e70b80a
remove modules