Use postPatch instead of prePatch to apply fix

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

pkgs/by-name/vi/visual-hexdiff/package.nix

@@ -13,10 +13,10 @@ stdenv.mkDerivation {
     url = "mirror://ubuntu/pool/universe/h/hexdiff/hexdiff_0.0.53.orig.tar.gz";
     sha256 = "sha256-M1bmkW63pHlfl9zNWEq0EGN1rpVGo+BTUKM9ot4HWqo=";
   };
-# Fix compiler error that wants a string literal as format string for `wprintw`
-  prePatch = ''
+  postPatch = ''
+  	# Fix compiler error that wants a string literal as format string for `wprintw`
     substituteInPlace sel_file.c \
-      --replace 'wprintw(win, txt_aide_fs[foo]);' 'wprintw(win, "%s", txt_aide_fs[foo]);'
+      --replace-fail 'wprintw(win, txt_aide_fs[foo]);' 'wprintw(win, "%s", txt_aide_fs[foo]);'
   '';
 
   patches = [