[exim] Lost connection during delay

I just noticed that exim doesn't clean up from a dropped connection
during a delay statement.

1) MX/client negotiate
2) client sends MAIL FROM
3) client sends RCPT TO
4) MX now stalls for 5 minutes from "delay = 5m" in the ACL
5) client drops the connection after a few seconds
6) MX continues to wait the full 5 minutes before putting the error in
the log and cleaning up

Running 4.50 and the state of the connection on the client was at
FIN_WAIT2 while the MX continued to wait. Wouldn't it make more sense
to free up those resources if the client goes away?