sympow: avoid undefined behaviour by increasing buffer size

pkgs/development/libraries/science/math/sympow/default.nix

···
 { lib, stdenv
 , fetchFromGitLab
+, fetchpatch
 , makeWrapper
 , which
 , autoconf
···
     sha256 = "132l0xv00ld1svvv9wh99wfra4zzjv2885h2sq0dsl98wiyvi5zl";
   };
 
-  patches = [ ./clean-extra-logfile-output-from-pari.patch ];
+  patches = [
+    ./clean-extra-logfile-output-from-pari.patch
+    (fetchpatch {
+      name = "null-terminate-dupdirname.patch";
+      url = "https://gitlab.com/rezozer/forks/sympow/-/merge_requests/5.diff";
+      sha256 = "sha256-yKjio+qN9teL8L+mb7WOBN/iv545vRIxW20FJU37oO4=";
+    })
+  ];
 
   postUnpack = ''
     patchShebangs .