Bug#361919: exim4: Dropping all hosts with ignore_target_hosts results in "host lookup did not complete"

[Magnus Holmgren]

Package: exim4
Version: 4.60-4
Severity: normal

The following routers for remote domains (the reason for this
configuration is left as an excercise to the reader)

-------------------------->8------------------------------
lookuphost:
  driver = dnslookup
  domains = ! +local_domains
  ignore_target_hosts = ! ::::/0 : ! 85.194.0.0/18 : ! 212.214.126.0/24 : ! 85.8.0.0/20
  same_domain_copy_routing
  transport = remote_smtp

smarthost:
  driver = manualroute
  domains = ! +local_domains
  transport = remote_smtp
  route_list = * smtpserver.stunet.se:mail.visit.se
  no_more
--------------------------8<------------------------------

give the following (partial) output for exim4 -d -bt
holmgren at lysator.liu.se:

-------------------------->8------------------------------
--------> lookuphost router <--------
local_part=holmgren domain=lysator.liu.se
checking domains
lysator.liu.se in "@ : ittma-hohah : localhost : kibibyte.se : mail.kibibyte.se"? no (end of list)
lysator.liu.se in "! +local_domains"? yes (end of list)
calling lookuphost router
lookuphost router called for holmgren at lysator.liu.se
  domain = lysator.liu.se
DNS lookup of lysator.liu.se (MX) succeeded
DNS lookup of mail.lysator.liu.se (AAAA) gave NO_DATA
returning DNS_NODATA
DNS lookup of mail.lysator.liu.se (A) succeeded
130.236.254.3 in "! ::::/0 : ! 85.194.0.0/18 : ! 212.214.126.0/24 : ! 85.8.0.0/20"? yes (end of list)
ignored host mail.lysator.liu.se [130.236.254.3]
mail.lysator.liu.se in hosts_treat_as_local? no (end of list)
fully qualified name = lysator.liu.se
host_find_bydns yield = HOST_FIND_AGAIN (1); returned hosts:
  mail.lysator.liu.se <null> MX=10 *
lookuphost router: defer for holmgren at lysator.liu.se
  message: host lookup did not complete
holmgren at lysator.liu.se cannot be resolved at this time:
  host lookup did not complete
search_tidyup called
--------------------------8<------------------------------

As you can see, there is no hint of DNS problems, so the
HOST_FIND_AGAIN is very strange. After downgrading to 4.60-1, the
problem went away. I suspect this might be caused by the fix to bug
#342619. More investigation to come...

-- System Information:
Debian Release: testing/unstable
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'stable'), (90, 'unstable'), (10, 'experimental')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.15-ittmahohah1
Locale: LANG=sv_SE.UTF-8, LC_CTYPE=sv_SE.UTF-8 (charmap=UTF-8)