Revert "nixos/docs: cache mergeJSON md conversion on baseOptionsJSON"

This reverts commit 52b0ad17e3.

we only needed this because mergeJSON was slow, but in the interim we
found a better solution to the slowness.

nixos/lib/make-options-doc/default.nix

@@ -99,14 +99,6 @@ let
 
   optionsNix = builtins.listToAttrs (map (o: { name = o.name; value = removeAttrs o ["name" "visible" "internal"]; }) optionsList);
 
-  pythonMD =
-    let
-      self = (pkgs.python3Minimal.override {
-        inherit self;
-        includeSiteCustomize = true;
-        });
-      in self.withPackages (p: [ p.mistune_2_0 ]);
-
 in rec {
   inherit optionsNix;
 
@@ -124,20 +116,17 @@ in rec {
 
   optionsJSON = pkgs.runCommand "options.json"
     { meta.description = "List of NixOS options in JSON format";
-      buildInputs = [ pkgs.brotli pythonMD ];
+      buildInputs = [
+        pkgs.brotli
+        (let
+          self = (pkgs.python3Minimal.override {
+            inherit self;
+            includeSiteCustomize = true;
+           });
+         in self.withPackages (p: [ p.mistune_2_0 ]))
+      ];
       options = builtins.toFile "options.json"
         (builtins.unsafeDiscardStringContext (builtins.toJSON optionsNix));
-      # convert markdown to docbook in its own derivation to cache the
-      # conversion results. the conversion is surprisingly expensive.
-      baseJSON =
-        if baseOptionsJSON != null
-        then
-          pkgs.runCommand "base-json-md-converted" {
-            buildInputs = [ pythonMD ];
-          } ''
-            python ${./mergeJSON.py} ${baseOptionsJSON} <(echo '{}') > $out
-          ''
-        else null;
     }
     ''
       # Export list of options in different format.
@@ -154,7 +143,7 @@ in rec {
           else ''
             python ${./mergeJSON.py} \
               ${lib.optionalString warningsAreErrors "--warnings-are-errors"} \
-              $baseJSON $options \
+              ${baseOptionsJSON} $options \
               > $dst/options.json
           ''
       }