Change:
I assume this derivation simply needs to be updated to use python 3 (and maybe bumped to a new version supporting it)
The new suffers from this problem too.

Discussion:
<ins> { stdenv, buildPythonPackage, fetchPypi, isPyPy , olefile , freetype, libjpeg, zlib, libtiff, libwebp, tcl, lcms2, tk, libX11 , openjpeg, libimagequant , pytest, pytestrunner, pyroma, numpy }: buildPythonPackage rec { pname = "Pillow"; version = "6.2.2"; src = fetchPypi { inherit pname version; sha256 = "0l5rv8jkdrb5q846v60v03mcq64yrhklidjkgwv6s1pda71g17yv"; }; # Disable imagefont tests, because they don't work well with infinality: # https://github.com/python-pillow/Pillow/issues/1259 postPatch = '' rm Tests/test_imagefont.py ''; checkPhase = '' runHook preCheck python -m pytest -v -x -W always runHook postCheck ''; propagatedBuildInputs = [ olefile ]; checkInputs = [ pytest pytestrunner pyroma numpy ]; buildInputs = [ freetype libjpeg openjpeg libimagequant zlib libtiff libwebp tcl lcms2 ] ++ stdenv.lib.optionals (isPyPy) [ tk libX11 ]; # NOTE: we use LCMS_ROOT as WEBP root since there is not other setting for webp. # NOTE: The Pillow install script will, by default, add paths like /usr/lib # and /usr/include to the search paths. This can break things when building # on a non-NixOS system that has some libraries installed that are not # installed in Nix (for example, Arch Linux has jpeg2000 but Nix doesn't # build Pillow with this support). We patch the `disable_platform_guessing` # setting here, instead of passing the `--disable-platform-guessing` # command-line option, since the command-line option doesn't work when we run # tests. preConfigure = let libinclude' = pkg: ''"${pkg.out}/lib", "${pkg.out}/include"''; libinclude = pkg: ''"${pkg.out}/lib", "${pkg.dev}/include"''; in '' sed -i "setup.py"  -e 's|^FREETYPE_ROOT =.*$|FREETYPE_ROOT = ${libinclude freetype}|g ; s|^JPEG_ROOT =.*$|JPEG_ROOT = ${libinclude libjpeg}|g ; s|^JPEG2K_ROOT =.*$|JPEG2K_ROOT = ${libinclude openjpeg}|g ; s|^IMAGEQUANT_ROOT =.*$|IMAGEQUANT_ROOT = ${libinclude' libimagequant}|g ; s|^ZLIB_ROOT =.*$|ZLIB_ROOT = ${libinclude zlib}|g ; s|^LCMS_ROOT =.*$|LCMS_ROOT = ${libinclude lcms2}|g ; s|^TIFF_ROOT =.*$|TIFF_ROOT = ${libinclude libtiff}|g ; s|^TCL_ROOT=.*$|TCL_ROOT = ${libinclude' tcl}|g ; s|self.disable_platform_guessing = None|self.disable_platform_guessing = True|g ;' export LDFLAGS="-L${libwebp}/lib" export CFLAGS="-I${libwebp}/include" '' # Remove impurities + stdenv.lib.optionalString stdenv.isDarwin '' substituteInPlace setup.py  --replace '"/Library/Frameworks",' ""  --replace '"/System/Library/Frameworks"' "" ''; meta = with stdenv.lib; { homepage = "https://python-pillow.github.io/"; description = "Fork of The Python Imaging Library (PIL)"; longDescription = '' The Python Imaging Library (PIL) adds image processing capabilities to your Python interpreter.  This library supports many file formats, and provides powerful image processing and graphics capabilities. ''; license = "http://www.pythonware.com/products/pil/license.htm"; maintainers = with maintainers; [ goibhniu prikhi ]; }; } </ins>

pyviz-comms = callPackage ../development/python-modules/pyviz-comms { }; <del> pillow = callPackage ../development/python-modules/pillow { inherit (pkgs) freetype libjpeg zlib libtiff libwebp tcl lcms2 tk; inherit (pkgs.xorg) libX11; </del> <ins> pillow = if isPy27 then callPackage ../development/python-modules/pillow/6.nix { inherit (pkgs) freetype libjpeg zlib libtiff libwebp tcl lcms2 tk; inherit (pkgs.xorg) libX11; } else callPackage ../development/python-modules/pillow { inherit (pkgs) freetype libjpeg zlib libtiff libwebp tcl lcms2 tk; inherit (pkgs.xorg) libX11; </ins> }; pkgconfig = callPackage ../development/python-modules/pkgconfig {