python311.pkgs.pip: fix eval (#537965)

pkgs/development/python-modules/pip/default.nix

@@ -29,6 +29,9 @@
 }:
 
 let
+
+  sphinxSupported = !sphinx.disabled;
+
   self = buildPythonPackage rec {
     pname = "pip";
     version = "25.3";
@@ -51,9 +54,8 @@ let
       flit-core
       installShellFiles
     ]
-    ++ lib.optionals (pythonAtLeast "3.11") [
+    ++ lib.optionals sphinxSupported [
       # docs
-      # (sphinx requires Python 3.11)
       sphinx
       sphinx-issues
     ];
@@ -61,13 +63,13 @@ let
     outputs = [
       "out"
     ]
-    ++ lib.optionals (pythonAtLeast "3.11") [
+    ++ lib.optionals sphinxSupported [
       "man"
     ];
 
     # pip uses a custom sphinx extension and unusual conf.py location, mimic the internal build rather than attempting
     # to fit sphinxHook see https://github.com/pypa/pip/blob/0778c1c153da7da457b56df55fb77cbba08dfb0c/noxfile.py#L129-L148
-    postBuild = lib.optionalString (pythonAtLeast "3.11") ''
+    postBuild = lib.optionalString sphinxSupported ''
       cd docs
 
       # remove references to sphinx extentions only required for html doc generation