From 67602e51e17584fc1b4e77f64ff77922e251aa10 Mon Sep 17 00:00:00 2001
From: Tobias Pflug <tobias.pflug@gmail.com>
Date: Wed, 27 Nov 2019 17:20:04 +0100
Subject: [PATCH] Fixes pypi fetching

- The first letter path segment in the url needs to be lowercased

  https://files.pythonhosted.org/packages/source/S/sqlalchemy/SQLAlchemy-1.3.11.tar.gz
  vs
  https://files.pythonhosted.org/packages/source/s/sqlalchemy/SQLAlchemy-1.3.11.tar.gz

- Rename fetchPypi to fetchFromPypi just to make it clear that we are
  not using fetchPypi from nixpkgs
---
 default.nix | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/default.nix b/default.nix
index 9ac920e..4cd032d 100644
--- a/default.nix
+++ b/default.nix
@@ -14,15 +14,19 @@ let
     else default
   );
 
-  # Fetch the artifacts from the PyPI index.
+  # Fetch the artifacts from the PyPI index. Since we get all
+  # info we need from the lock file we don't use nixpkgs' fetchPyPi
+  # as it modifies casing while not providing anything we don't already
+  # have.
   #
   # Args:
+  #   pname: package name
   #   file: filename including extension
   #   hash: SRI hash
   #   kind: Language implementation and version tag https://www.python.org/dev/peps/pep-0427/#file-name-convention
-  fetchPypi = lib.makeOverridable ({ pname, file, hash, kind }:
+  fetchFromPypi = lib.makeOverridable ({ pname, file, hash, kind }:
     pkgs.fetchurl {
-      url = "https://files.pythonhosted.org/packages/${kind}/${builtins.substring 0 1 file}/${pname}/${file}";
+      url = "https://files.pythonhosted.org/packages/${kind}/${lib.toLower (builtins.substring 0 1 file)}/${pname}/${file}";
       inherit hash;
     });
 
@@ -138,7 +142,7 @@ let
             broken = ! isCompatible python.version pkgMeta.python-versions;
           };
 
-          src = fetchPypi {
+          src = fetchFromPypi {
             pname = pkgMeta.name;
             inherit (file) file hash;
             # We need to retrieve kind from the interpreter and the filename of the package