Using different branches for different modules becomes hard in a monorepo when branching is a global operation. You can only have a single branch checked out in

Using different branches for different modules becomes hard in a monorepo when branching is a global operation. You can only have a single branch checked out in your working copy then. The only solution I can think of is to create a copy within the monorepo to create de facto branches without regular VCS support. This would be kind of terrible.