The submodule linter appears to have been disabled in [1]. As Matthew notes in [2], perhaps we should probably open a ticket to track how to restore it.

Ryan S.
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[1] https://gitlab.haskell.org/ghc/ghc/commit/a39a3cd663273c46cf4e346ddf3bf9fb39195c9d
[2] https://gitlab.haskell.org/ghc/ghc/commit/a39a3cd663273c46cf4e346ddf3bf9fb39195c9d#note_213227