I got the following error message:

> fatal: Not a git repository: ${BASEDIR}/ghc/.git/modules/.arc-linters/arcanist-external-json-linter

I guess this is because my local directory is not named “ghc”, but “ghc-
linear”. In my opinion, the repository should not assume that a local
copy of it resides in a directory of a certain name. Is this a GHC issue
or an issue with your linear-types branch?