is duplicated by:

• SR-7386 switching between similar packages breaks swift package update

Issue Description:

Suppose I fork a dependency to test a change, and adjust my Package.swift to point to it. Later, after a few builds, I decide it was a bad idea and revert my Package.swift to the old repo. Now, I must `rm -rf .build` to compile.

What appears to happen is the next swift build will fail with something like

error: terminated(128): git -C /My/Package/.build/repositories/some-repo.git--4899257340567273111 remote update -p
error: product dependency 'SomeModule' not found

which is because `some-repo.git` actually has a different suffix number, so there is content in `.build/repositories/some-repo.git-7785354365974529063` that prevents the build from continuing. `swift package clean` doesn't resolve this, and I need to `rm -rf .build` manually.