There was a bug in the command line cabal-install tool that broke emacs' haskell mode on Windows.

It was ultimately a result of two file paths being compared as strings rather than as file paths thus the comparison was sensitive to drive capitalisation. Under circumstances that I am yet to fathom the call to cwd on Windows returns "C:/...", other times it returns "c:/...", which made the bug that more bizarre and harder to pin down.

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