fixup! OxCaml: setup CI

Author: vouillon

tools/ci_setup-oxcaml.ml

@@ -19,6 +19,8 @@ let roots =
   ; "await"
   ]
 
+let additional_others = StringSet.of_list [ "spawn" ]
+
 let omitted_others = StringSet.of_list [ "odoc" ]
 
 let omitted_js = StringSet.of_list [ "basement"; "sexplib0"; "ppxlib_jane"; "spawn" ]
@@ -332,7 +334,10 @@ let pin nm =
 let pin_packages () = sync_exec pin (StringSet.elements do_pin)
 
 let install_others others =
-  let others = StringSet.elements (StringSet.diff others omitted_others) in
+  let others =
+    StringSet.elements
+      (StringSet.union (StringSet.diff others omitted_others) additional_others)
+  in
   ignore (Sys.command ("opam install -y " ^ String.concat " " others))
 
 let clone ?branch ?(depth = 1) nm src =