grib-api: Add grib-api to pythonPackages

This provides a default method for using the grib-api python bindings.

pkgs/development/libraries/grib-api/default.nix

@@ -25,6 +25,10 @@ stdenv.mkDerivation rec{
                   pythonPackages.python
                 ];
 
+  propagatedBuildInputs = stdenv.lib.optionals enablePython [
+                  pythonPackages.numpy
+                ];
+
   cmakeFlags = [ "-DENABLE_PYTHON=${if enablePython then "ON" else "OFF"}"
                  "-DENABLE_PNG=ON"
                  "-DENABLE_FORTRAN=ON"

pkgs/top-level/python-packages.nix

@@ -12176,6 +12176,14 @@ in {
     };
   };
 
+  grib-api = if (isPy27) then
+      (pkgs.grib-api.overrideAttrs (oldattrs: {
+    name = "${python.libPrefix}-" + oldattrs.name;
+  })).override {
+    enablePython = true;
+    pythonPackages = self;
+  } else throw "grib-api not supported for interpreter ${python.executable}";
+
   gspread = buildPythonPackage rec {
     version = "0.2.3";
     name = "gspread-${version}";