RPC: allow 'epoch' as a valid Time.rpc_arg

src/lib_base/time.ml

@@ -113,10 +113,18 @@ module T = struct
       ~descr:(Format.asprintf "A date in seconds from epoch")
       ~destruct:
         (fun s ->
+           if s = "none" || s = "epoch" then
+             Ok epoch
+           else
+             match of_notation s with
+             | None -> begin
                  match Int64.of_string s with
-           | exception _ ->
+                 | exception _ -> begin
                      Error (Format.asprintf "failed to parse time (epoch): %S" s)
-           | v -> Ok v)
+                   end
+                 | t -> Ok t
+               end
+             | Some t -> Ok t)
       ~construct:Int64.to_string
       ()