Delayed update...

pkgs/lumpy.nix

@@ -12,6 +12,12 @@
           extension = "zip";
           sha256 = "e5cf3fdf13401885e8eea8170624ec96225e2174eb0c611c6f26dd33b489e3ff";
         };
+        nativeCheckInputs = [
+          prev.pytest
+          # "hypothesis" indirectly depends on numpy to build its documentation.
+          prev.hypothesis
+          prev.typing-extensions
+        ];
       });
     };
   };