sage: replace flask-babel version pin by patch

pkgs/applications/science/math/sage/default.nix

@@ -14,16 +14,6 @@ let
 
       cvxopt = super.cvxopt.override { inherit glpk; };
 
-      # https://github.com/sagemath/sagenb/issues/437
-      flask-babel = super.flask-babel.overridePythonAttrs (attrs: rec {
-        version = "0.9";
-        src = attrs.src.override {
-          inherit version;
-          sha256 = "0k7vk4k54y55ma0nx2k5s0phfqbriwslhy5shh3b0d046q7ibzaa";
-        };
-        doCheck = false;
-      });
-
       # python packages that appear unmaintained and were not accepted into the nixpkgs
       # tree because of that. These packages are only dependencies of the more-or-less
       # deprecated sagenb. However sagenb is still a default dependency and the doctests

pkgs/applications/science/math/sage/sagenb.nix

@@ -36,6 +36,14 @@ buildPythonPackage rec {
   # tests depend on sage
   doCheck = false;
 
+  patches = [
+    # work with latest flask-babel
+    (fetchpatch {
+      url = "https://github.com/sagemath/sagenb/commit/ba065eca63dd34a383e4c7ba7561430a90fcd087.patch";
+      sha256 = "1lamzsrgymdd618imrasjp6ivhw2aynh83gkybsd7pm1rzjcq4x8";
+    })
+  ];
+
   meta = with stdenv.lib; {
     description = "Sage Notebook";
     license = licenses.gpl3Plus;