Bug: outputs [@explicit_arity] even though it takes a tuple

Using refmt --parse re --print ml --interface false, this reason code:

type msg =
  | Request (command_msg, option updateOp);

let msgToString = fun
  | Request (cmd, _) => "Request\n  cmd: " ^ Command.toString cmd;

Converts to this ocaml code:

type msg =
  | Request of (command_msg* updateOp option)

let msgToString =
  function
  | ((Request ((cmd,_)))[@explicit_arity ]) ->
      "Request\n  cmd: " ^ (Command.toString cmd)

Request is defined as taking a tuple, so [@explicit_arity] should not be present.

I wanted to automatically generate an interface file, but this causes compilation to fail under ocamlc -i with this error message:

Error: The constructor Request expects 1 argument(s),
       but is applied here to 2 argument(s)

$ refmt --version
Reason 1.13.7 @ d13c6bd

Start by reproducing the issue with the refmt --parse re --print ml --interface false command and inspect the refmt entry point for Reason-to-OCaml printing. The generated output should not add [@explicit_arity] for this tuple constructor, and the result should compile successfully with ocamlc -i.