perl-net-dns-resolver-programmable used the undocumented and internal
method Net::DNS::rcodesbyname [0], and that interface is no longer
exposed.

This patch, copied from [1], makes the program check for the existence
of the method before trying to use it.

[0]
<https://rt.cpan.org/Public/Bug/Display.html?id=95901>

[1]
<https://rt.cpan.org/Public/Bug/Display.html?id=95901#txn-1575108>

diff --git a/lib/Net/DNS/Resolver/Programmable.pm b/lib/Net/DNS/Resolver/Programmable.pm
index 1af72ce..e09a2f0 100644
--- a/lib/Net/DNS/Resolver/Programmable.pm
+++ b/lib/Net/DNS/Resolver/Programmable.pm
@@ -203,8 +203,10 @@ sub send {
     if (defined(my $resolver_code = $self->{resolver_code})) {
         ($result, $aa, @answer_rrs) = $resolver_code->($domain, $rr_type, $class);
     }
-    
-    if (not defined($result) or defined($Net::DNS::rcodesbyname{$result})) {
+
+    if (not defined($result)
+         or defined($Net::DNS::Parameters::rcodebyname{$result})
+         or defined($Net::DNS::rcodesbyname{$result})) {
         # Valid RCODE, return a packet:
         
         $aa     = TRUE      if not defined($aa);
refs</a><a class='active' href='/guix/log/gnu/packages/selinux.scm'>log</a><a href='/guix/tree/gnu/packages/selinux.scm?id=3211f45f0b741d5dea97de3745804881d7446d34'>tree</a><a href='/guix/commit/gnu/packages/selinux.scm?id=3211f45f0b741d5dea97de3745804881d7446d34'>commit</a><a href='/guix/diff/gnu/packages/selinux.scm?id=3211f45f0b741d5dea97de3745804881d7446d34'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/selinux.scm'>
<input type='hidden' name='id' value='3211f45f0b741d5dea97de3745804881d7446d34'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=3211f45f0b741d5dea97de3745804881d7446d34'>root</a>/<a href='/guix/log/gnu?id=3211f45f0b741d5dea97de3745804881d7446d34'>gnu</a>/<a href='/guix/log/gnu/packages?id=3211f45f0b741d5dea97de3745804881d7446d34'>packages</a>/<a href='/guix/log/gnu/packages/selinux.scm?id=3211f45f0b741d5dea97de3745804881d7446d34'>selinux.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/selinux.scm?id=3211f45f0b741d5dea97de3745804881d7446d34&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-01-15 14:46:44 +0100'>2019-01-15</span></td><td><a href='/guix/commit/gnu/packages/selinux.scm?id=44d10b1f722856ab8e9b942804aa7ef33e2ef739'>gnu: Separate Python core packages from the rest.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2018-06-22 00:20:11 +0200'>2018-06-22</span></td><td><a href='/guix/commit/gnu/packages/selinux.scm?id=bb6c3d2332d74e268f5d48b39b92b97cea1acab3'>gnu: libsemanage: Return #t from all phases.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-03-25 05:02:07 -0400'>2018-03-25</span></td><td><a href='/guix/commit/gnu/packages/selinux.scm?id=927c52c4ab148e83861e48bb07b08588a386043b'>gnu: libselinux: Use invoke.</a><span class='msg-avail'>...</span></td><td>Mark H Weaver</td></tr>
ae'>build: Change default substitute server to "ci.guix.gnu.org".</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* config-daemon.ac: Replace "ci.guix.info" with "ci.guix.gnu.org".
* doc/guix.texi (SUBSTITUTE-SERVER): Likewise.
* etc/substitutes/ci.guix.gnu.org.pub: New file.
* Makefile.am (dist_pkgdata_DATA): Add it.
* guix/scripts/build.scm (%default-log-urls): Update.
* guix/scripts/substitute.scm (%default-substitute-urls): Likewise.
* guix/store.scm (%default-substitute-urls): Likewise.
* guix/self.scm (miscellaneous-files): Add "ci.guix.gnu.org".


</td></tr>
<tr class='logheader'><td><span title='2018-12-04 10:57:56 +0100'>2018-12-04</span></td><td class='logsubject'><a href='/guix/commit/etc/substitutes?id=6a837b6062ab405f6ca6d9c0163836769098d89b'>etc: Add "ci.guix.info.pub" public key file.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* etc/substitutes/ci.guix.info.pub: New file.
* Makefile.am (dist_pkgdata_DATA): Add it.
* guix/self.scm (miscellaneous-files): Add
"share/guix/ci.guix.info.pub".


</td></tr>
<tr class='logheader'><td><span title='2018-11-06 00:04:11 +0100'>2018-11-06</span></td><td class='logsubject'><a href='/guix/commit/etc/substitutes?id=aa919fbc890c5438166083f9ff02e4b1968a182b'>maint: Move substitute public keys to etc/substitutes.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* berlin.guixsd.org.pub, hydra.gnu.org.pub: Move to...
* etc/substitutes: ... here.  New directory.
* Makefile.am (dist_pkgdata_DATA): Adjust accordingly.


</td></tr>