botの自動更新でインストールが失敗してて気づいた。手元でも失敗。
$ swift sdk install --checksum c701d3f5bb69464fd443f20c4748cab068c9c6d8f6995f1ba5be70022778d21f https://download.swift.org/swift-6.1-branch/static-sdk/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a_static-linux-0.0.1.artifactbundle.tar.gz Downloading a Swift SDK bundle archive from `https://download.swift.org/swift-6.1-branch/static-sdk/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a_static-linux-0.0.1.artifactbundle.tar.gz`... Downloading 100% [=====================================================================================================] Downloading swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a_static-linux-0.0.1.artifactbundle.tar.gz Swift SDK bundle archive successfully downloaded from `https://download.swift.org/swift-6.1-branch/static-sdk/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a_static-linux-0.0.1.artifactbundle.tar.gz`. Verifying if checksum of the downloaded archive is valid... Downloaded archive has a valid checksum. Swift SDK bundle at `https://download.swift.org/swift-6.1-branch/static-sdk/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a/swift-6.1-DEVELOPMENT-SNAPSHOT-2025-03-12-a_static-linux-0.0.1.artifactbundle.tar.gz` is assumed to be an archive, unpacking... Error: tar: Error opening archive: Unrecognized archive format