linkBinIntoOwnPackage: protect against empty doc/man outputs

pkgs/by-name/trivial-builders/package.nix

@@ -98,7 +98,13 @@
     paths = if lib.isList path' then path else [ path' ];  #< coerce to list
     paths' = (lib.map (p: "bin/${p}") paths) ++ [ "share/doc" "share/man" ];
   in
-    linkIntoOwnPackage pkg paths' {}
+    linkIntoOwnPackage pkg paths' {
+      postFixup = ''
+        # not all packages ship manpages or docs,
+        # but we can't know if that's the case upfront, generically.
+        mkdir -p "$doc" "$man"
+      '';
+    }
   ;
 
   deepLinkIntoOwnPackage = pkg: { outputs ? [ "out" ] }: symlinkJoin {