Can't pip install from msys2

[glandium]

This is the output while pip install'ing mercurial from msys2:

  Running setup.py (path:c:/users/ta2291~1/appdata/local/temp/pip-build-_zfnyo/mercurial/setup.py) egg_info for package mercurial
    Running command python setup.py egg_info
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "c:/users/ta2291~1/appdata/local/temp/pip-build-_zfnyo/mercurial/setup.py", line 910, in <module>
        extmodules.append(setup_zstd.get_c_extension(name='mercurial.zstd'))
      File "contrib/python-zstandard/setup_zstd.py", line 128, in get_c_extension
        compiler.compiler_type)
    Exception: unhandled compiler type: mingw32