error building haskell-src-exts

[simonmichael]

pier is looking great, thank you ! I am experimenting with it again inspired by your informative bayhac video.

I see this failure with haskell-src-exts. It doesn't look like a Setup.hs thing:

$ pier build haskell-src-exts
haskell-src-exts-1.20.2: building library
Error when running Shake build system:
* Library haskell-src-exts
* Command: haskell-src-exts-1.20.2: building library

_pier/artifact/5aLeCjWPqG5-J8O8MrpdlaRXH8qarjFFTjJIzGEEm9c/Language/Haskell/Exts/InternalParser.hs:24592:1: error:
    parse error (possibly incorrect indentation or mismatched brackets)
      |
24592 | (CompletePragma (happy_var_1 <^^> happy_var_4 <** ([happy_var_1] ++ fst happy_var_2 ++ com ++ [happy_var_4])) (snd happy_var_2) ts)
      | ^

[philderbeast]

@simonmichael I'm also seeing the same failure trying to build hlint and doctest test suites for #50.