For a long time, I have had sieve-manage-default-port set to "sieve".
Apparently, sieve-manage ignored that in the past.  Now that
sieve-manage-default-port is used properly by sieve-manage-open, I was
getting the following traceback:

Debugger entered--Lisp error: (error "Format specifier doesn't match argument type")
  format(" *sieve* %s:%d" "localhost" "sieve")
  sieve-manage-open("localhost")
  sieve-open-server("localhost" nil)
  sieve-manage("localhost")
  call-interactively(sieve-manage t nil)
  execute-extended-command(nil)
  call-interactively(execute-extended-command nil nil)

I could obviously change my sieve-manage-default-port port to 2000, but
is there any reason not to use the following patch (which works for me)
instead?