Build fails when standalone

[eutampieri]

The swift build fails with Fatal error: Duplicate values for key: 'Async': file /BuildRoot/Library/Caches/com.apple.xbs/Binaries/swiftlang/install/TempContent/Objects/BNI_assert_lightweight/swift-macosx-x86_64/stdlib/public/core/8/HashedCollections.swift, line 8108

The complete output is this: Fetching https://github.com/vapor/core.git Fetching https://github.com/vapor/async.git Fetching https://github.com/apple/swift-nio.git Fetching https://github.com/apple/swift-nio-zlib-support.git Cloning https://github.com/apple/swift-nio.git Resolving https://github.com/apple/swift-nio.git at 1.9.2 Cloning https://github.com/vapor/async.git Resolving https://github.com/vapor/async.git at 1.0.0-rc.1.1 Cloning https://github.com/vapor/core.git Resolving https://github.com/vapor/core.git at 3.4.1 Cloning https://github.com/apple/swift-nio-zlib-support.git Resolving https://github.com/apple/swift-nio-zlib-support.git at 1.0.0 Fatal error: Duplicate values for key: 'Async': file /BuildRoot/Library/Caches/com.apple.xbs/Binaries/swiftlang/install/TempContent/Objects/BNI_assert_lightweight/swift-macosx-x86_64/stdlib/public/core/8/HashedCollections.swift, line 8108 Illegal instruction: 4
I was trying to investigate why swift package update was stuck on this dependency of vapor.

[vzsg]

You shouldn't bother with this package. It was abandoned during the development of Vapor 3, so the master branch is broken. This is kept around for the tagged versions that Vapor 2 depends on.