[exim] address lookups stripping off plus-addresses

I'm poking around at plus-addressing with exim+cyrus and it's not working
right. After some time I figured out that the extended address was not
being used for the envelope recipient. With --debug +all it seems that
that the recipient address is being rewritten by the redirect router.

I've tried setting the rewrite = false on that router but the behavior
hasn't changed any. I've included the relevant part of the config below.

ldap_users:
  driver                     = redirect
  data                       = ${lookup ldap{LDAP_USER_LOOKUP}}
  domains                    = +local_domains
  rewrite                    = false
  allow_fail                 = true
  allow_defer                = true
  local_part_suffix          = +* : -*
  local_part_suffix_optional = true
  file_transport             = local_file
  pipe_transport             = local_pipe
  more                       = false

When the user is matched in ldap_users the response data includes the
destination address that should be used, but the suffix is gone. This
happens with rewrite set to either true or false

Any ideas?

-- 
Eric A. Hall                                  http://www.eric-a-hall.com/
Network Technology Research Group                    http://www.ntrg.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/