How to create an opam switch from a modified version of the compiler/stdlib?


I need to test some changes to the stdlib.
How can I create a new opam switch using my modified version of the sources?


ok, there is testing with opam in there:

There is also this option if you want to pin a specific commit: `opam switch create ocaml-variants.4.12.0+BS` - #9 by emillon