やっぱりswift package edit Bだった。
$ git reset --hard HEAD is now at 66ed003 Update TweetupKit $ swift package edit TweetupKit Fetching https://github.com/swift-tweets/tweetup-kit.git Fetching https://github.com/swift-tweets/OAuthSwift.git Fetching https://github.com/kylef/Commander.git Fetching https://github.com/koher/PromiseK.git Fetching https://github.com/kylef/Spectre.git Cloning https://github.com/swift-tweets/tweetup-kit.git Resolving https://github.com/swift-tweets/tweetup-kit.git at 0.2.1 Cloning https://github.com/koher/PromiseK.git Resolving https://github.com/koher/PromiseK.git at 3.0.0-alpha.4 Cloning https://github.com/kylef/Spectre.git Resolving https://github.com/kylef/Spectre.git at 0.8.0 Cloning https://github.com/swift-tweets/OAuthSwift.git Resolving https://github.com/swift-tweets/OAuthSwift.git at 2.0.0-beta Cloning https://github.com/kylef/Commander.git Resolving https://github.com/kylef/Commander.git at 0.8.0 swift package edit TweetupKit 3.07s user 2.89s system 53% cpu 11.056 total $ (cd Packages/TweetupKit;git checkout master) Previous HEAD position was 71f0117... Merge pull request #11 from swift-tweets/dev-0.2.1 Switched to branch 'master' Your branch is up to date with 'origin/master'. $ swift build Updating https://github.com/koher/PromiseK.git Updating https://github.com/swift-tweets/OAuthSwift.git Updating https://github.com/kylef/Commander.git Updating https://github.com/kylef/Spectre.git Updating https://github.com/swift-tweets/tweetup-kit.git Fetching https://github.com/OAuthSwift/OAuthSwift.git Cloning https://github.com/OAuthSwift/OAuthSwift.git Resolving https://github.com/OAuthSwift/OAuthSwift.git at master Compile Swift Module 'PromiseK' (2 sources) Compile Swift Module 'Commander' (9 sources) Compile Swift Module 'OAuthSwift' (24 sources) …
(edited)