ocaml-base-compiler package conflict when updating opam-debian-switch

[Silas <silascoder@proton.me>]

Hey all,

I've been directed to take a look at opam-debian-switch to identify ways to 
contribute to the project, and I've been trying to replicate the workflow 
described in the Readme.

The first thing I noticed is that I was unable to run make because it seems 
that there are some new packages added to the debian repo that have not 
been added to the pkgmap.json, so I made those changes. Once, I was able to 
run make, I ran into a different error.

When running setup.opam.sh as builder, I get an error at the step of 
installing from opams-to-install.txt. It seems to be unable to install 
ocaml-base-compiler:

[ERROR] Package conflict!
  * No agreement on the version of ocaml-base-compiler:
    - ocaml-base-compiler
    - (invariant) -> ocaml-base-compiler = 4.13.1
    You can temporarily relax the switch invariant with `--update-
invariant'
  * Incompatible packages:
    - ocaml-base-compiler
    - (invariant) -> ocaml-system = 4.13.1

What should I do about this error? Is there something wrong with ocaml-
base-compiler rather than opam-debian-switch? 

Is there a mistake I could have made in the workflow? I tried schroot with 
both sid and stable, and I got the same error twice.

My guess is that I shouldn't just mark ocaml-base-compiler with "!".

Best,
Silas