how to cancel a TCP.create_connection?

[hannesm]

I try to implement a protocol which sets custom connection timeouts, so my attempt was to Lwt.cancel (or Lwt.pick [ create_connection ... ; sleep timeout ]), but it turns out that this doesn't do anything, instead after the connection establishment timeout, the create_connection task continues to run. Is there a way to cancel them?

[hannesm]

a "trick" seems to be to use another mutable variable (or Lwt_switch.t or similar).