Merge master into staging-next

pkgs/development/interpreters/python/build-python-package-wheel.nix

@@ -8,7 +8,7 @@
 attrs // {
   unpackPhase = ''
     mkdir dist
-    cp $src dist/"''${src#*-}"
+    cp "$src" "dist/$(stripHash "$src")"
   '';
 
   # Wheels are pre-compiled

pkgs/development/interpreters/python/fetchpypi.nix

@@ -0,0 +1,28 @@
+# `fetchPypi` function for fetching artifacts from PyPI.
+{ fetchurl
+, makeOverridable
+}:
+
+let
+  computeUrl = {format ? "setuptools", ... } @attrs: let
+    computeWheelUrl = {pname, version, python ? "py2.py3", abi ? "none", platform ? "any"}:
+    # Fetch a wheel. By default we fetch an universal wheel.
+    # See https://www.python.org/dev/peps/pep-0427/#file-name-convention for details regarding the optional arguments.
+      "https://files.pythonhosted.org/packages/${python}/${builtins.substring 0 1 pname}/${pname}/${pname}-${version}-${python}-${abi}-${platform}.whl";
+
+    computeSourceUrl = {pname, version, extension ? "tar.gz"}:
+    # Fetch a source tarball.
+      "mirror://pypi/${builtins.substring 0 1 pname}/${pname}/${pname}-${version}.${extension}";
+
+    compute = (if format == "wheel" then computeWheelUrl
+      else if format == "setuptools" then computeSourceUrl
+      else throw "Unsupported format ${format}");
+
+  in compute (builtins.removeAttrs attrs ["format"]);
+
+in makeOverridable( {format ? "setuptools", sha256 ? "", hash ? "", ... } @attrs:
+  let
+    url = computeUrl (builtins.removeAttrs attrs ["sha256" "hash"]) ;
+  in fetchurl {
+    inherit url sha256 hash;
+  })