sage: fix relevant broken symlinks, ignore others (#380444)

pkgs/by-name/sa/sage/package.nix

@@ -48,8 +48,8 @@ let
     ];
     language = "sage";
     # just one 16x16 logo is available
-    logo32 = "${sage-src}/src/doc/common/themes/sage/static/sageicon.png";
-    logo64 = "${sage-src}/src/doc/common/themes/sage/static/sageicon.png";
+    logo32 = "${sage-src}/src/doc/common/static/sageicon.png";
+    logo64 = "${sage-src}/src/doc/common/static/sageicon.png";
   };
 
   jupyter-kernel-specs = pkgs.jupyter-kernel.create {

pkgs/by-name/sa/sage/sage-src.nix

@@ -99,6 +99,9 @@ stdenv.mkDerivation rec {
     "-p1"
   ];
 
+  # harmless broken symlinks to (not) generated files used by sage-the-distro
+  dontCheckForBrokenSymlinks = true;
+
   postPatch = ''
     # Make sure sage can at least be imported without setting any environment
     # variables. It won't be close to feature complete though.